If Celestia is ever hit by the Harmony Beam, she'll revert back to Solaria
It is heavily hinted that Celestia is discorded Solaria. It has also been said by Discord, that the Elements of Harmony work by restoring the natural order of things. Since Discord is the god of change (and chaos), his machinations moved Celestia away from her 'natural state'. Hence, restoring her with the Elements (accidentally or on purpose) will turn her back to Solaria. Celestia is going to revert back to Solaria in Mente.
It doesn't make sense to play up Solaria so much if she wasn't going to reappear sooner or later. Which leads on to... The Uber Ethereal is going to be the Godzilla Threshold that makes Discord reawaken Solaria from Celestia.
Remember the Ethereal overwhelming Twi with two words? Pre-alicorn Twi was still one of the strongest if not the strongest unicorn around. Now since Rank Scales with Asskicking is very much in play in this series, just how strong must the Uber Ethereal be? Maybe strong enough that none of the Princesses can seriously hurt him. Now, it's already been established that the aliens' adherence to their own type of Order immunises them to the Elements of Harmony. I don't either think that Arad is going to suddenly introduce Rainbow Power. So the most likely solution would be for Discord to reawaken the Superpowered Evil Side and hope that, when the Uber Ethereal is dead, Solaria is also weakened enough that he can pop the seal back on her can.The MEC suits are the X-COM equivalent of Space Marine Dreadnoughts
We see the CMC sneak into a part of the human compound that is designated as the MEC pilot care area. Then we see one of them lying on a bed with grave injuries. Thus it seems that X-COM is using ME Cs to allow their soldiers to continue fighting when they otherwise would have been unable to due to injury.- Confirmed in chapter 26, though they can also be used by mostly healthy soldiers at some cost.
EXALT's Alpha agents are a preview of what will happen to humanity if the aliens win
Think about it, all alien units that are even slightly biological have massive amounts of genetic manipulation to the point where redundant and atrophied organs are common. The Alpha agents are gene modded to a ridiculous degree and can tear regular humans limb from limb with their bare hands. The cannon shows that defeated species are absorbed into the Ethereal collective to be used against the next species encountered. Maybe this is how the Sectoids, Mutons and Thin Men were 'recruited'. Crushed between the Ethereal's existing forces and hordes of superpowered traitors. The version of EXALT faced by XCOM is not the original.
The Canon! version of EXALT is a centuries old, opportunistic Ancient Conspiracy backed by the rich and shady. Stardust! EXALT is essentially the Cult of Sirius in suits. Assuming that both versions have the same origins something must have happened to Stardust! EXALT in order for them to go from a clandestine, nebulous organisation of Blackshirts that avoid contact with alien forces where possible to fanatical Les Collaborateurs that openly field their troops as auxiliaries and infiltrators.There are many possible reasons for this, Stardust! EXALT could have been co-opted by the Ethereals as early the moment they found out about its existence or Stardust! EXALT could have been considered an ally, on a sort of 'lets start a proxy war' level, up until their failed attempt at Grand Theft Durand. This, or a similar incident could have caused Stardust! EXALT to be taken under direct alien command in order to nip any potential Chronic Backstabbing Disorder in the bud.
Lana Jenkins is a sociopath
A high functioning sociopath to be precise. Traumatic childhood event? Lana blasted her berserk father with a shotgun at age 12; then had to be a substitute parent for her younger brothers while her mum worked. Check. Lack of empathy? While not completely without empathy, Lana's borderline bullying of Matt through their (massively one-sided) prank war shows that for her empathy is something normally found in the 'off' position. Check. Refusal to accept the possibility of being wrong? Chapter 20. 'nuff said. Refusal to allow morality and/or ethics to obstruct the pursuit of a goal? The entirety of her Shipper on Deck mentality. Check. The reason Lana could be considered high functioning is that she is capable of forming genuine relationships with people and using her single-mindedness and lack of ethics to help them, in her own slightly twisted way.