I think if Xehanort is going to have 13 embodiments then there should be at least six Keyblade wielders. If for some reason, Ventus, Aqua, and Terra cannot be reconstituted, maybe they can give us some bull that Terra's heart was responsible for reviving Axel and then Aqua would be responsible for recreating Xion and... well, Sora has Ventus' heart within him and we've already seen Roxas. I still don't understand why the two of them need to be together to be whole. If they can be brought back, well then... I'd still like to see the return of Roxas and Xion. That would complete the theme of threes. Three Greeks, three Nips, three "x" names... maybe they'll work in the Kairi aspect popularized by Monty Oum where she transforms into Naminé and fights like Nu or whatever her name is. Or... what if Kairi and Naminé become separate beings? That would bring the total to 10. Will two new characters be introduced to create a team for Naminé? A guy named Kaze? Another guy named Yama? ...Yamacha?