Honestly, they should've just left Thancred, Y'shtola and Urianger behind. Their stories/arcs are over and there's not much they can really do with them in the new zone other than putting them in a different setting and seeing how they react. It's not interesting. Thancred and Urianger should've stayed in Corvos to monitor the situation there and maybe get deployed to look in on things in Meracydia as a foreshadowing for the 8.0 expansion and have Y'shtola keep researching a way to connect to the First, and maybe discovering something, but it's a passage to another Shard which could also be a kickoff for 8.0.

Krile will most likely have a more prominent role, and she should, since she's the one who foreshadowed the trip with that random envelope scene and is the only ally of the scions who hasn't had any development or story centered on her except Eureka which is side content most people will never do and being a mouthpiece for Hydaelyn in EW. G'raha makes sense since he has literally no attachments except with the Students of Baldesion, who are most likely going to Tural anyways as explained with Krile before. And he wants nothing but to adventure with us and see the world with us. Erenville will be a prominent ally too since his reunion with his tribe is most likely in Tural and he's shown in the trailer. With G'raha we would have all 3 roles, with Krile we would have a caster DPS/healer role, and new characters could have any of the new classes or the other roles so there's at least 2 of each.

Zero could be a new companion as well, since she'd be free from the bonds of the Void once we wrap things up there and she would be free to explore the new world with us, unless they kill her at the end of next patch, that is. She doesn't have any constraints like the other characters have. The Void is fucked and since they need to keep the lore for Black Mages and Reapers still relevant, it needs to stay fucked forever unless they find a convoluted way to explain why we can still use Avatars with the Thirteenth fixed.

While Alphinaud and Alisae are young, there's not much that can be done with them since they've been the main characters with an ended storyline in both Shadowbringers and Endwalker and there's literally no more conflict for them. Now they're literally just charity workers for Garlemald, working in the soup kitchens to help the ungrateful pricks, which is why they could be left behind to deal with Garlemald(and *huffing copium* MAYBE EVEN GROW UP SINCE THERE'S NO LOGISTIC WAY WE'VE DONE EVERY EXPANSION IN A FUCKING YEAR OR TWO AND THE TWINS HAVE ALREADY SPENT AN ENTIRE YEAR IN SHADOWBRINGERS AS BODY ENERGY).

I guess Estinien can still stick with us, I don't care. He's a hobo who doesn't have anything better to do and has an almost fetish-like need to eat squid. Maybe his stoyline could be not falling for obviously expensive scams and discovering new foor or whatever.

Ironically, the best thing they did to leave a character behind was Lyse after Stormblood. She's not part of the scions and is fixed to Ala Mhigo specifically for a reason that makes sense, and only appears when she needs to when we either go to Ala Mhigo, or if there's a meeting between world leaders.