Im curtain Hayner & gang will be back, they were good friends with Kairi & Sora also I would'nt rule out the possibility of them being Keyblade weilders to n Sora's going to need all the help he can get right, I dont see them doing anything Major in the final battle, but they can contribute by fighting off Unverse, Heartless, & Nobodies, while the 7 lights go head to head with the 13 darknesses