So. Um. Back to talking about the movie.
I guess it would be possible to strip down and summarize KH1 to the point that there are only a few Disney worlds: Wonderland, Agrabah, Neverland, and arguably Monstro (depending on how much of Riku's arc is preserved.) This list is a bit Golden/Silver Age-heavy, so I could see Wonderland being swapped out for a newer princess world. Monstro might also be substituted for something else because "Fantastic Voyage" type plots work better as game levels than movie subplots.
The rumor specifically said that that this movie is going to be a live action/CGI hybrid, so I've seen people speculate that the division is going to be world-based, with the KH worlds being live action and the Disney worlds being CGI animation. That could be interesting, but it would be better if they fully committed to the hybrid idea. Yes, have the 3D animated movies be represented by CGI, but use 2D animation for the traditionally animated movies, and use stop motion if Halloweentown makes it in. But this would take a lot more effort than just having everything in one medium, so I don't know if they'd actually do it.
I don't know how they'd do Donald and Goofy in live action. That sounds kind of, well, goofy.