Didn’t Nomura mention something about Sora and Riku being in 2 different versions of the same world in the secret ending? I don’t remember his exact wording, but I think it was something to that effect, but not the same as Toy Box being a copy of a world, right?
IMO this is a perfect opportunity to introduce the Tim Burton Alice in Wonderland. This would make a beautiful, expansive world, it could take over the live-action property in the game, and it could tie into the multiple versions of the same world.