What I'd really like to see...

KH + Devil May Cry = KH2.

THAT'D be the ultimate game. Have Sora be able to do a bit more with the Keyblade(s) and get around a lot more fluently and stuff. Hell, Sora doesn't need the guns that Dante had; he'll have two friggin' Keyblades, which is plenty of an advantage!

But since that's only wishful thinking, I'd like to be able to switch control of characters, like famish99 mentioned. As well as perhaps a bit more variety of magic spells, and be able to activate some skills with different button pushes, like in Devil May Cry; you know, not have to select to do Ars Arcanum in the little window, just do it; perhaps through means of another shortcut menu you could select to do certain skills.

And have an items shortcut menu! Slow access to Elixirs killed me the first few times I tried to fight (SPOILER)Sephiroth.