Breaking down my thoughts on this leak for fun
-Disney Worlds: Seem pretty plausible, but most of them are just the popular speculation and Pooh was already leaked. Nothing to really convince me one way or the other.
- Original Worlds: Also pretty popular speculation; Radiant Garden and Keyblade Graveyard have already been seen in trailers.
-Summons: I feel like the summons in KH can be almost anything so I have no way of judging this list.
-Other notes on Disney stuff: I always thought having Disney characters stick to their own worlds or original worlds was a Disney mandate, so this "leak" is starting to sound like bunk to me. I remember people speculating that the 626 experiments might be collectibles a couple years ago, but haven't heard anyone talk about that for a long time
-Optional Disney Bosses: This seems like a lot of unique optional bosses, but they do all seem like good choices to meet outside their worlds and represent a good variety of popular and obscure characters. If the "leak" was just this, I might think it was plausible.
-Non-Disney Secret Bosses: lol wut. No way is the notoriously camera shy Nomura going to put himself in the game as an optional boss. Ardyn seems pretty unlikely to show up either, given how upset Nomura still seems about what happened with XV.
-Easter Eggs: These types of things sound like they would be pretty fun, though I can't believe that The Jungle Book is going to replace Pooh.
-Disney Worlds Saved for Future Games: A lot of popularly requested worlds that seem unlikely to make it in. Our "leaker" knows how to pander to fans.
So in conclusion, I find this leak to be super fake and mostly a compilation of previous fan speculation repackaged as what's actually going to happen. Though it would be hilarious if most of this stuff was true after all.