I like to theorize on a possible appearance of Namine in this game.
We might learn exactly why she has those memory manipulation powers. KHII shows that even Namine doesn't know why.
Namine acting as one of those projection types that only one person can see. And that person is Kairi. Think about it, either anywhere, or just in place of Kairi's reflection.
Continuing from number two. Namine might Kairi some helpful tips, if the latter is playable. It'll be like the Cheshire Cat from American McGee's Alice.
Number two is inspired by Handsome Jack's role in Tales from the Borderlands.