I kinda don't want to see any of them...they are whole again so they don't have too much importance...Except the apprentices who probably have info on TAV and Xehanort the apprentice.
But if they all come back, I only want them to be cameos. 358/2 Days could have been used to expand on all of their characters (not just the few they did give life to) but they didn't so I see no point of trying to expand on them now in the next main installment of KH. BBS might add a little bit of character to some of them, but I also find that time wasted when we are trying to figure out TAV, MX, DS, MTAV, and Xehanort who is to come.
Probably Axel, Saix, and Xigbar will appear and hoping Zexion since he was the youngest apprentice and probably the most knowledgeable.
Marluxia might just because he was the main villain in CoM and his minor role in 358/2 days.