I want to gouge my eyes out after seeing that...
Part of the charm of the KH series was the constant introduction of Square characters into the series. Heck, Sora himself is a Square character. I also can't see how two behemoths like Mario and Mickey can exist in the same game. It'd be impossible to coordinate between the two companies about their two flagship characters as to which one would be "king" of which area. There were no such troubles with the Square characters cuz, really, none of them diserve to be King more than Mickey did. They all have character flaws, while Mickey has none. With two characters having no character flaws? It'd be impossible to weave a half decent story out of that.
I'd *love* to see a KH game on the Wii, though. It'd be interesting to see how similar the controls would be to LoZ on that console. Also, considering that I have no plans to purchase a PS3 at any point in the forseeable future, putting KH3 on said system would simply be a waste of an amazing game to me.
For the record, I haven't played KH2 yet. I'm still on KH1, just after beating the 9th world.