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Tontu (beta) and Jellybean have settled in the nowhere space of Wood Man's house
Their last scene at the end of Season 1 showed they ended up at the ruins of Hilda's old house. So the only house in the direct vicinity with enough nowhere space for them to live in was Wood Man's home. It would make sense for them to go live there (with or without his knowledge).

If the Netflix series gets a second season, it will adapt Hilda and The Stone Forest and Hilda and The Mountain King
Seeing as this is the only two of the graphic novels not adapted by the Netflix series, it seems inevitable that it would be adapted in the second season. And seeing as this particular graphic novel ends on a cliffhanger and the resolution hasn't been released yet, the Netflix series will either adapt it as the season 2 finale, with the resolution being the premiere of season 3 or if the resolution does get released before season 2, put those two together as the season finale. Since "Hilda and The Mountain King" was released in 2019, it is very likely that season 2 will adapt "Hilda and The Mountain King" as the season finale.
  • Jossed; "The Stone Forest" is used as the season finale, while "The Mountain King" is adapted as a movie, released on December 30th 2021.
    • Prior to the movie's official release, Luke Pearson gave a tiny clue on Twitter to read ahead in the "Mountain King". So the likelihood of the graphic novel being the movie is high.
    • Several months later after season 2 aired, Megan Ferguson announced that the movie has wrapped, and many months later after that, Silvergate Media announced that the movie is titled, "Hilda and The Mountain King".

Hilda is a Half-Human Hybrid
It would explain the blue hair.

  • This actually makes a lot of sense. We never see or hear of Hilda's father, and considering that she and her mum have lived in the wilderness isolated from humans for all of Hilda's life, it's not much of a stretch to assume her dad might have been some sort of magical creature.

The world of Hilda operates on I Know Your True Name.
This may be why we never learn many of the magical creatures' names, and especially why everyone just seems to accept it. The magical creatures are naturally wary of their names being used to harm them, so don't share them with humans.
  • Except we do at least learn one Vitra's nickname. Probably not his real name though.

David isn't (entirely) human either.
Like Hilda and her blue hair, David also has something that makes him stand out; he's the only character with Black Bead Eyes, while all other human characters have normal looking eyes. And as they say, eyes are windows of the soul, so this could be a reveal that he's not fully human.
  • If that's true, it could also explain why insects are inexplicably attracted to him.
    • Expanding on the theory above; notice how at the end of season 2, when the young troll becomes human, she has black bead eyes just like David? Perhaps David (and the few other characters to have these kind of eyes) are also former trolls turned human.

The Origins of Trollberg was Written by the Winners.
If Hilda is anything like others shows we've seen (such as Star vs. the Forces of Evil), then it is a safe that the trolls in the legend of the city were actually decent creatures that were driven out of their homeland by snooty villainous humans who would later build that wall to keep the trolls from taking it back.
  • Judging by the events of Hilda and the Mountain King, there's some amount of truth to it, but the humans in this verse did it unknowingly (they didn't knew, that the progenitor of all trolls sleeps under Trollberg).

The girl in Trevor's group of friends is related to David
She is the only other human with Black Bead Eyes, like him. While probably not a sibling (we would have seen her at his house otherwise), she could definately be a cousin of him.

The other wood person we see on one of the portraits in The House in the Woods isn't a relative/old flame of Wood Man's, but Wood Man himself, albeit younger

As he grew older, he went through the process of what constitutes for his species' version of balding.

Going off the above theory, Wood Man secretly Hates Being Alone to some degree, but has no idea how to express it

While he's very good at hiding it, there's the possibility that for his abrasiveness and indifference, the idea of consistently being part of someone's life is one he's quite drawn to. The aforementioned other wood person isn't actually real, but rather a manifestation of his feelings of isolation. Not to mention how he would frequently barge into Hilda and Johanna's old cabin on short notice. In E11, Wood Man's advice to Hilda, coupled with him admitting that he genuinely considers her a friend and suggesting she visits him once in a while and vice versa, could be interpreted as him taking small but significant steps to overcome this.

If Hilda and The Stone Forest does wind up being the Season 2 finale, the second-to-last episode of the season will end on Hilda being grounded.
In the novel proper, Hilda sneaks out with Raven after a nasty spat with Johanna, bringing along Frida (and nearly getting her killed). By the time she gets back, Johanna has already found out, and promptly forbids Hilda from leaving the house without her until further notice. How the show will handle this is up to interpretation, but with how it's altered and expanded upon certain elements from the books, it's possible they may add in an additional consequence of Hilda's impulsiveness to warrant such a punishment.
  • Jossed; while Stone Forest is the season finale, Hilda getting grounded actually happens earlier in the season, at the end of episode 7, and is resolved again at the start of episode 9.

Hilda and the Mountain King will avert Shapeshifting Excludes Clothing
Either Hilda's troll form will keep her clothes, or she will magically regain he clothes upon turning back to a human. Netflix is more liberal than, say, Nickelodeon or Disney Channel, but they'll likely want to avoid even implying Hilda's fate in the comic.
  • Or they could have what happens in the comics where Tontu quickly reveals that he had brought along a spare set of Hilda's clothes and then have a cut to after Hilda gets dressed.
  • Jossed. Like in the comics, Hilda is left nude when she transforms back into a human, with Tontu fortunately having brought spare clothes.

The season 2 episode involving the Ghost Ship is the one that'll result in Hilda being grounded.
Mainly because, out of all the adventures we got clips of in the season 2 trailer, it's the one where Johanna directly witnesses the danger that Hilda has gotten herself into. Johanna's annoyed, possibly angry, cry of ,"Hilda," that follows the ghost ship passing through their house also doesn't bode well for Hilda.

The Raven makes trips back and forth between Trolberg and North America
According to a deleted scene from The Troll Circle, he has other places to go and is not just famous in Trolberg. This would make sense considering he's a Thunderbird - a creature of North American folklore - in a mostly Scandinavian setting. Because he's a supernatural Giant Flyer, it isn't so farfetched that he could simply fly across continents.

Frida and David will have an active role in restoring Hilda to human form
In the graphic novel "Hilda and the Mountain King", reuniting Hilda and the troll child with their real mothers broke the changeling spell and reverted both of them back to their normal selves, while Frida and/or David played no part. But in the animated series, Frida is a much more important character than she was in the graphic novels, and now she has started learning magic. It would be a waste of a good plot/character if the adaptation of Mountain King didn't give her a major role in reverting the spell.
  • While Frida and The Witches should definitely play some role in reverting the spell, It should still be Hilda and Baba reuniting with their real mothers that breaks the spell. Because Motherhood is the Theme of that Story.
Although i wouldn't mind seeing the spell being temporarily reverted by Frida and the witches like there only able to revert it for a Few Minutes to an Hour.
  • Jossed. Frida tries to restore Hilda to human form, but her attempts at using witch magic fail. Like in the comics reuniting Hilda with Johanna and Baba with her mother breaks the spell.

Frida and David will reunite with Hilda first in the Mountain King adaptation.
It is very likely that Frida and David will reunite with Hilda in the 70-minute special first, before Johanna later on. This is because, at some point, Frida learned a teleportation spell that can easily transport them to the Stone Forest and find Hilda in her troll form. Fans can predict that an emotional group hug between the three is in order.
  • Jossed. Hilda reunites with Johanna first. She meets up with Frida and David later.

If Hilda gets a season 3, then the first three or four episodes will be the Mountain King adaptation special, but split into parts.
When Season 2 finished off open-ended, and that the 70-minute movie special is on the way, if Hilda gets renewed for a season 3 (due to Luke Pearson having plans for continuing the show, despite the original graphic novel series ending), it is very likely that the movie will be split into three or four episodes, making it the first multi part episode arc for the series.
  • Can also be a tearjerker and heartwarming moment if one of the episodes in the multi-part arc end with Hilda tearfully reuniting with Frida and David or Johanna.
    • The first part has been confirmed, but the second part is yet to determined.
    • Jossed; the movie will adapt "The Mountain King", so season 3 will be entirely original stories.

The movie will happen immediately after "The Stone Forest
CONFIRMED: Silvergate Media confirmed on their website that the movie special is titled, Hilda and the Mountain King.

Hilda will get a season 3 after the 70-minute movie
Even after her troll-body experience and after managing to stop Erik Ahlberg, there is still room for more adventures yet to be discovered in both Trolberg and outside Trolberg.
  • CONFIRMED: Ako Mitchell announced on Twitter that a third season is in production, while Silvergate Media made an official confirmation on their website several months later.

Erik will become a Hero with an F in Good
With The Mountain King more than likely being the basis of the movie, there's a chance that by the climax, Erik will end up seeing the error in his ways much like he did in the novel. Following this, Erik will legitimately try to actually help others for real this time... but he will still go about it in a very rash and oftentimes boneheaded way.
  • It seems that with the release of The Mountain King, Erik has pulled a Heel–Face Turn. Whether it sticks remains to be seen.
    • Not likely; at the end of the movie, Erik retires as head of the safety patrol, ending his story arc.

The Keeper of the bell tower is Hilda’s father
This theory has become quite popular right before Season 2. Luke Pearson mentioned via Word of God that Hilda’s father is “still around, but separated.” And the bellkeeper fits the criteria for her father with many supportive arguments to back up this theory.
  • He has faint blue-colored streaks on the sides of his hair, similar to Hilda’s distinctive blue hair. Also, the bellkeeper seems to be the ONLY other character in the show so far to have this color of hair.
  • He is quick to look out for Hilda when she arrives at the bell tower in the middle of the night, giving her refreshments and explaining the history of the bell tower. If he wasn’t Hilda’s father, why would a stranger such as him who barely even knew Hilda let her come into his office and give her these details?
  • It is revealed later on that he listened in on Hilda’s communication with Frida via walkie-talkie. And as he catches sight of Hilda, he immediately says her name. Only, there wasn’t a scene shown when the bellkeeper got to learn Hilda’s name, and Hilda didn’t tell him that her name was Hilda, so how could he have figured it out on his own?
  • And finally, when the mission is accomplished, the bell keeper decides to shake hands with Hilda in a sign of bonding over the experience.
Later, when Hilda approaches her mother and greets her, Hilda looks behind her. The bell keeper is there in the distance, with his hood up and looking at Hilda with a fond smile. But then he looks next to Hilda and his smile stops to a look of surprise when he is presumably looking at Johanna, almost as if he recognizes her right away. With that, he decides to walk away seemingly to avoid confrontation with Hilda’s mother.

The Movie will be adapted from Hilda and The Mountain King
  • Confirmed.

The Great Raven will return in Season 3
It was bad enough that they adapted him out from Season 2 even though HE WAS THE ONE WHO SAVED HILDA IN THE ORIGINAL COMIC, so having him back nest season as a semi-regular or recurring would be enough to make up for taking him out in the first place.
  • While Season 3 has been confirmed, it is still yet to be updated if the Raven will appear.

Trundle will be voiced by Luke Pearson
Well, this wouldn't be the first time a show's creator voiced a one-eyed antagonist who manipulated a young girl into releasing him, and cause mayhem against humanity.

Trevor's mother is/was a Marra
In the Yule Lads episode, Frida suggests that Trevor may have gotten his Jerkass behavior from his mother. In the previous season, Marras are shown to take the forms of teenage girls and gossip among each other, and Frida herself hung out with a group of them. Frida also addresses Trevor's mom as "Queen Naughty", which sounds a lot like some nickname a teenager would make up. Kelly, the Marra whom Frida befriended, was also shown to have a mother, though it is unknown if these powers could be passed down or if a Marra can keep her powers into adulthood, a subject that could be explored in the future. On the surface, Trevor and his mother seem to dislike Hilda for being different - or to the latter a "witch" - but the latter secretly believes Hilda could expose her identity as a Marra and so strictly forbids her son from making contact with the blue-haired girl.

Trundle's Leitmotif will be based on, In the Hall of the Mountain King
Once Hilda meets Trundle, there will be a musical cue that sounds like the titular musical piece. This will serve as a clue to Trundle's real identity. Once Trundle is freed from his prison, the actual "Mountain King" theme will be played.

Future Hilda was trying to warn the Present Hilda about Trundle
At the climax of "The Fifty Year Night", Hilda encounters a version of herself from the future. If you listen carefully, Future Hilda was trying to tell her present self to find someone before being swallowed by the Time Worm. Future Hilda was warning Present Hilda about Trundle, and how her deal with him to change her back to a human led to his eventual release from his prison, and his plan to destroy Trolberg. That's why Future Hilda said it was for her present self's own good.
  • Future Hilda does not appear in the movie, and since Trundle's plan was ultimately thwarted with only Trundle himself as a casualty, there was no need for Hilda to travel back in time.

Hilda is going to have a major Heroic BSoD in the Mountain King adaptation
In the original Graphic Novel, after she found out that Trundle tricked her into releasing him, Hilda immediately blamed herself for it. But she managed to pull herself through, and proceeded to stop the Mountain King. For the adaptation however, considering that Hilda lied to her mother in "The Beast of Cauldron Island" and was punished for it, Hilda will instead break down in tears after Trundle lied to her and ultimately gives up stating that nothing can stop him. However, Frida, David, and Johanna step in and tell Hilda that it wasn't her fault, and letting her know that she is a courageous young adventure who tries to do the right thing. This gives Hilda the encouragement to let go of her guilt, and try to stop Trundle.
  • Jossed. Like in the comics, Hilda immediately sets out to stop Trundle. However, she does have two emotional breakdowns in the film, one where her first reaction upon seeing herself and the second where Trylla is unable to help her.

Alternative casting choices for Trundle
In case that the above guess for Luke Pearson voicing Trundle gets jossed, here are some other possible actors to voice Trundle. Feel free to add to the list.

There will be a special end credits song for the Hilda 70-minute movie special
Instead of the usual "Hilda's Theme", there will be a song that will be played over the closing credits of the upcoming "The Mountain King" adaptation.
  • CONFIRMED: Here is the song titled, "Another Road" performed by Rachel Aggs, of the British Indie-Rock band, "Shopping".

Here is a list of possible songs to be featured for the upcoming movie. Feel free to add to the list.

The changeling spell will be expanded upon
In "The Mountain King" graphic novel, Tontu deduced that Hilda and Baba were placed under a changeling spell. For the adaptation, Alfur steps in and explains that the spell was supposed to be forbidden. Alfur further explains that long ago, various mythical beings used the changeling spell on their children in order to give them a better life amongst the humans. However, many parents discovered that their own children were taken and replaced with strange creatures. This ultimately led to various wars between the humans and mythical beings. As the wars worsen, the leaders of all mythical beings have decided that this has gone long enough. And finally, they all declared that all Trolls, Elves, Nisse, etc., shall never use the changeling spell ever again. Alfur, Tontu and Johanna all deduced that the Troll Mother probably found the means to use the spell to give Baba a better life, despite being forbidden to do so.
  • This leads to the Troll Mother getting in trouble for breaking the rule (using the forbidden spell).
    • However, The giant Troll (later revealed to be Trundle's brother), steps in and persuades the others not to punish the Troll Mother for using the changeling spell. Instead, the giant Troll offers her to have Baba be trained as his apprentice. As such, both Trolls agreed.
  • Jossed. None of the above happens in the adaptation, which, aside from David and Frida's subplot, is a very faithful adaptation of the comic.

Hilda will grow up to become an adventurer and author of the journals where she write about her adventures

The Marra will join Trundle

When and if Hilda turns back into a human, she will be afraid to go outside Trolberg again
Think about it, she was magically transported to the forest against her will, transformed into a Troll which is horrific all on its own, and then there's Trundle. Even the most fearless person in the world would start developing some type of phobia after going through all that. But, Frida and David might tell Hilda that she was very brave, even if she was outside the wall.

Season 3 could take place outside of Trolberg during a 4-week vacation trip
Think about it. We've seen a lot of Trolberg. So Season 3 may or may not take the Sequel Goes Foreign path where we see Hilda, Johanna, Twig, Alfur, as well as Frida and David, with their respective parents' permission, go on a vacation to a destination outside of Trolberg and Hilda finds more adventure and mysteries yet to unfold. And, if goes according to plan, the first episode of the season will start with Hilda and the others preparing for the trip while encountering another supernatural activity and will end with Hilda and the gang heading off for the trip.

The remaining 12 episodes will involve Hilda and the others reaching their destination and see what mysteries and excitement unfold. The final episode of the season will have one last supernatural encounter on their last day and end with Hilda and her family and friends heading back to Trolberg.

  • While Season 3 has been confirmed and is also announced as the final season, the plot of the season is unknown and yet to be determined.

Erik Ahlberg will be arrested in the 70-minute movie special
Erik Ahlberg had been a jerkass throughout season 2, and all he wants is fame for himself over helping others. It takes its toll when he refuses to listen to Hilda when she warns him about Amma.
  • Jossed. He retires from the Trolberg safety patrol and seems to have taken a Heel–Face Turn.

The 70-minute movie special will end with Trolberg being destroyed
In a Bittersweet Ending, while Hilda is able to stop Erik Ahlberg, the aftermath of the earthquake and Trundle's attack results in the city of Trolberg being destroyed.
  • The movie can possibly be a Bookends of the first 2 episodes of the series. Hilda's former cabin in the wilderness is destroyed by Jorgen at the end of the 2nd episode of the 1st season. The movie will end with Trolberg destroyed in the aftermath of the final battle to stop Trundle from waking up Amma.
  • This seems highly unlikely since the graphic novel shows Hilda managing to stop the Trolberg Safety Patrol from attacking the Trolls. Which led to Trolberg being safe and sound. Therefore, the adaptation should have Trolberg remain intact.
  • Also, there is going to be a third season coming up so it really wouldn't make sense if the entire city is destroyed.
  • Jossed. Like in the comic, Trolberg survives the crisis.

If Season 3 is the final season, the season have Hilda and Johanna moving back to the Wilderness, but this time, Frida, David, and Tontu will join them
  • If mentioned above is confirmed, then Hilda and Johanna will have to move back to the Wilderness but this time Frida and David as well as Tontu will join them. Much like the 2nd episode of the 1st season, Hilda brought along memories of the Wilderness to Trolberg. But when she goes back to the Wilderness, she'll have memories of Trolberg with her, with that being Frida and David, who are both Hilda's close friends.
    • Season 3 has been confirmed and is also announced as the final season, but the plot is yet to be determined.

The series finale credits will be different
  • For the final episode of the series as a whole, instead of the usual black background credits, it will instead end with the camera panning up to a sunset or night sky as the end credits roll while a Triumphant Reprise of "Hilda's Theme" plays for the last time.
    • Semi-confirmed: Season 3 is announced to be the final season, but the plot is yet to be determined.

Hilda's father is trapped in that beach/planet/dimension/wherever it is Victoria ended up at the end of "The Windmill"

Hilda is a vegetarian
  • In the Mountain King book, there's a part where Hilda (as a troll) and the other trolls are eating meat, and Hilda asks for something "more vegetarian." Additionally, all the food in the Hilda Creatures game is veg based. Not only that, but you never see her eating meat in the show; it's mostly quiche and cucumber sandwiches. Hilda has always seemed like the animal-lover type, so her being a vegetarian makes a lot of sense.

Hilda is Happily Adopted
  • It's on the reach-y end of things, but it does actually help to explain at least two things: her blue hair (obviously) and why we've never heard or even seen a word or glimpse to her dad's likeness or whereabouts. Whether or not this ties into the above Half-Human Hybrid theory is up to its own interpretation.

Season 3 follows Hilda and Johanna learning about their family history with Frida and David
  • Face it. There's still questions about Hilda's blue hair as well as her dad. This leads Hilda to yet another mystery where she finds out about her dad with her friends and family's help.

The movie adaptation of Mountain King will have an extra plot thread focusing on Frida and David finding their own way to locate Hilda
  • Which takes them to Baba's cave (while Hilda is dealing with Trundle's bells), and to Trundle's cave. Where they discover Trundle's true nature.
    • The trailer does show a scene where Frida uses some spell that lets her see Hilda as a troll, so this could be true.

The movie will end with Hilda and Johanna playing the board game the latter bought at the beginning of The Stone Forest
  • As a sign of their improved relationship and deciding to start over.

If Frida and David have their own plot thread in the Mountain King movie, they will go to the Marra for help
  • And perhaps blackmail Kelly into helping them find Hilda by threatening to tell the other Marra about Fluff-bun.
  • Jossed. The Marra never even show up in the film.

"Hilda and The Mountain King" will have a special outro
This will replace the typical black-screen default credits in the actual series.

The Life of Hilda was written by Hilda herself in her room, during the time she was grounded
Given the fact that "The Beast of Cauldron Island" ended with a musical number by Hilda herself, it is presumed that Hilda wrote this song and played it on the guitar during the time she's grounded, and Johanna overheard it overnight and thought about her daughter's safety and her love for adventuring.

Season 3 will be the final season
  • CONFIRMED: Silvergate Media announced that "Hilda" season 3 will be its last.

Frida will find out how to break the changeling spell in the movie
In the graphic novel, the characters broke the spell entirely by accident. Johanna just tried to find Hilda and brought Baba along, resulting in both Hilda and Baba being reunited with their real mothers. That this was the condition needed to break the spell was a lucky coincidence, as no-one involved knew about it beforehand. In the movie, Frida will be a character, and the trailer actually shows David asking her if the spell can be reversed. Likely, this will encourage Frida to research the spell (perhaps with help from Tildy and/or Kaisa) and thus discover they must return Hilda and Baba to their real mothers for the spell to be broken, after which Johanna sets out with Baba to do just that.
  • Which would also give a justification why Tontu brings Hilda a spare set of clothes; he knew they were going to break the spell and she would need them. In the graphic novel, he is just Crazy-Prepared.
  • Jossed. She tries to undo the spell's effects, but it doesn't work.

The series finale ends with Hilda moving from Trolberg to see the world
In a Bookends to the second episode from the first season, Hilda and her mum would leave Trolberg and move to another part of the world that has yet to be explored and Hilda will have to say goodbye to the friends and creatures she met along the way, as well as a tearful goodbye to David and Frida, her first human friends. The series will end with the car leaving the gates of Trolberg for the very last time and a somber version of "Hilda's Theme" plays over the credits to end the series.

Season 3 will give the series the proper send-off
CONFIRMED: According to Megan Ferguson, Netflix allowed the crew to give the show a proper send-off for the final season.

Erik Ahlberg is not what he seems
In the same vein as Ducktales 2017s Flintheart Glomgold and the Stan's brother reveal, it turns out the man claiming to be Erik Ahlberg is not using his real identity, and is in fact not even related to the ancestor he claims to be descended from, Edmund "Trollslayer" Ahlberg. This would explain why the Rat King couldn't find anything on him. Because there is no Erik Ahlberg; he is a fake identity. He's lied about who he is as a hero. Why not lie about who he is entirely down to the name?

Erik Ahlberg will live among the trolls
In the movie, he discovers the hidden caves the trolls hide away in during the day and that they can be activated using certain passwords (in this case, "Baba"). An episode of the third season will involve Hilda returning to the mountain to visit the trolls and, much to her shock, discovering that Ahlberg is now living amongst them in order to learn about troll society as atonement for his past actions as well as his ancestor Edmund's. At the most extreme, he could end up becoming a troll the same way Hilda did and learn to harness troll magic - only to get corrupted with power and try to become the new Mountain King.

If Hilda wasn't a Half-Human Hybrid before, she is one now.
Despite having had her humanity restored, Hilda still seems to carry some characteristics of trolls. She can still comprehend them, was shown to still be able to leap far for a human, was able to carry Trundle's eye after being turned back (lifting Johanna alone was enough to get her to comment on Hilda's strength and the eye is slightly bigger than her), and despite being out in the open without any clothes at night in the mountains (where we can assume its freezing), didn't seem to feel cold at all, and dressed less warmly than she typically does for mountains in the epilogue when she goes hiking with Trylla and Baba. At the end of the movie, she even described herself as being able to live like a troll at times. Though being turned back into a human possibly tempered some of these traits. She had minor trouble translating Amma's thoughts, and part of her increased leaping length may be her longer legs. We may see in season 3 that she may still have enhanced strength, the ability to roar, and a small degree of irritation to bells (just light auditory irritation) and sunlight (like flaky skin necessitating sunscreen).

David will be turned into something
Frida became a witch and Hilda became a troll, so it's only fair that David also becomes some sort of magical being. Given his association with insects, it's possible he will encounter fairies - which have yet to appear in the series - and be transformed into one, temporarily of course.

Season 3 will be set during the year Time Skip in the epilogue of the movie
The movie ends with a flash forward of 1 year later; the night of the Trolls has been established, and Hilda and Frida are notably taller now that they are a year older. Of course season 3 can pick up where this epilogue left off, but it would make more sense to turn the season into an Interquel set during that year, and show what happened in the immediate aftermath of the movie.
The series finale will have a final credits song as a sendoff to say goodbye...
What better way to end a perfect series with a perfect sendoff song to say farewell to a fearless blue-haired girl...

Here is a list of potential finale end credits songs. Feel free to add to the list.

The credits for the series finale will be a Bookends to the end credits for the first episode of the series.
In a Bookends to the first episode, the end credits for the series finale of Hilda will start with the well-known crossfade transition from the final scene to the closing credits as one of the finale credits songs mentioned above play the episode out, or "Hilda's Theme" plays for the very last time. And when the credits fade-in, you, and everyone else around you, know that it is officially over.

Hilda is a Demigod.

The scrapped content for The Mountain King will be refitted for Season 3.
  • Specifically David's mum interacting with the Bell Keeper, and Kaisa standing up to the Comittee of Three.

Deerfoxes are native to the Avatarverse.
Such Mix-and-Match Critters wouldn't be remotely out of place there. They're so little known on Earth because it's not their usual stomping grounds when they visit a material world. Those light bridges are actually part of the Avatarverse's spirit world.

The third season will touch more on other characters' parents and family
The aforementioned scene of David's mother interacting with the Bell Keeper - who may or may not be Hilda's dad. There's also the implication that Trevor is a bully because of his mother.

Hilda will be dealing with some mild PTSD in season 3.
Considering that Hilda dealt with being turned into a Troll against her will and Trundle's betrayal, season 3 will have Hilda coping with the overall trauma and eventually coming to terms with it by the end.
  • Unlikely. Considering the time skip at the end of the movie.

Victoria Van Gale is the Arc Villain for season 3
Surely, Victoria Van Gale would turn up again. She would be out for revenge for Hilda for sabotaging her plan to destroy Trolberg. Can be Darker and Edgier when Victoria even tries to kill Hilda...

How to free Amma without destroying Trollberg in the process
Frida, Kaisa, Matilda and the Committee of Three will use the biggest teleportation spell ever and let Amma change places with the ground under a completely uninhabited place close to Trollberg.