Usopp will have some level of precognition.The latent ability provides a bonus to his sharpshooting skills, as well as gives him some insight into future events. However, it's balanced out by two flaws: Cassandra Truth and a tendency to see worst-case scenarios, making him naturally paranoid. His tall tales serve two purposes: in-universe, it's a method of coping with and relaying his visions in a way that doesn't get automatically rejected by others. On a meta level, meanwhile, it's a way of challenging the GM, who has to eventually translate his stories into the campaign in some fashion.
At least one of the players will be the opposite gender of their character.Chopper seems like a good bet, but Franky or Brook would be far funnier. Plus, the latter would provide an easy way to crack jokes about the "Mary Sue becoms the Straw Hat's Musician" trend prior to his joining.
Usopp's player will eventually want to stop because they're not having fun.Considering Luke lives by the Rule of Fun, this would come as a major gut punch to him... much like the actual arc.
Rika will eventually become Nico Robin's playerAt least if the purple speech bubbles are any indication.
Before playing Robin, Rika will play Vivi.And her decision to switch to Nico Robin will echo Cory's shunting his character template onto Roronoa Zoro. In her case, however, it will be based more on roleplaying, feeling that it'd be more in-character for Vivi to choose to stay in her kingdom, and wanting a more properly empowered character.
Franky's future player will play Vivi.Hey, the color-coding would match...
Luke's All-Ones "Diplomacy Die" has a single 20 on it.To account for those rare occasions when Luffy actually says the right thing.
DM will take over as Gamemaster for the Alabasta and Water 7 Arcs......with Vivi as a GMPC and Franky simply being a major antagonist before things go Off the Rails.
Sogeking will be the GM showing everyone how to play Usopp 'right'.After Phil Rage Quits, claiming his character's too weak and Can't Catch Up to the others, the GM takes over and uses his character sheet to 'create' Sogeking, proving otherwise.
Sogeking will be the Luke playing Usopp or giving Phil advice on how to do so.Luke is the one that has noticed that Usopp may just be the most broken character ever. Luke seems like the type that would have Usopp wear a mask and pretend to be a superhero. Heck, Luke would probably use a real life mask to signify that he's switching between Luffy and Sogeking.
DM is SO going to be Nico Robin.Robin's morbid sense of humor, skillset and backstory just fit so perfectly with an ex-Killer Gamemaster who is trying to be more of a roleplayer.
DM is going to be Sanji.Sanji is right up there with Luffy and Zoro in terms of power. This tells us that he was made by a min/maxer. He's going to be introduced after DM's current character is defeated. What better replacement character could there be? There is a good backstory and Sanji is over-roleplayed just like Kurahadol to the point that the GM has to provide an in-character reason for Sanji to join the other PCs.
Franky is a former villain from one of DM's old campaigns.Back then, he utterly trounced Luke, Cory, and the current GM's characters. Now that they're running a higher-powered campaign, however, GM eventually decides to borrow and bring back their old adversary to work out some grudges they still hold towards him. DM's signature color being aqua blue like Franky's is a bit of color-coded Foreshadowing, as well as her mentioning that all her villains had perfectly good Backstories that they simply never got a chance to learn before they died.
Phil will fully become part of the group at either the Arlong Park arc or the Little Garden arc.While Phil is fitting in with the group just fine right now, he's still an outsider unfamiliar with the terms of the game. In One Piece, Usopp generally feels left out of the group due to being weak until around these points. The Arlong Park arc might work during his fight with Chuu, where he gets the resolve to actually fight instead of just run away, while the Little Garden arc provided a lot of character development for Usopp and led him to become more active in chasing his dreams and being a warrior. For Phil, this could be either him realizing how much effort the group actually puts into the game and resolving to have fun along with them, or getting a more active role in the story and generally having more fun doing so than he was before.
Phil will fall out with the group around the Water 7 arc.In the same breath as the above WMG, Usopp doesn't have many major fights after the Little Garden arc (minus Mr. 4 and Miss Merry Christmas, where he got trounced). Phil might start to feel left out of the things that got him drawn into the group in the first place and leave the group for a little while, only to realize that he's come to enjoy his time with them and come back as "Sogeking" to try and make amends.
Rika will play as Sanji
GM will play Sanji, and DM will take over the gameThis would account for Sanji being an "NPC" in the story, and the enemies becoming more and more overpowered.
Future Strawhat PC's PredictionsSanji (GM):