When it comes to returning Disney worlds it comes down to the following factors and it's very subjective:
- Which Disney worlds Nomura and the team want to reuse again for the specific KH game
- The themes that the specific returning Disney worlds based on that Disney or Pixar film have in common to the theme of the specific KH game (e.g. Friendship, Trust, Connections, Promises, etc.)
- The Story the world can offer
- The gameplay value and environment that the world can offer.
- Variety
- Disney giving Requests and suggestions to which Films they want to see added in the game to Nomura and the team (e.g. Big Hero 6 in KH3)
Tbh prior to it's KH3 reveal, I Initially didn't think we were coming back to Olympus/Olympus Coliseum for
Kingdom Hearts III cause I thought KH2's story of the world got a great sendoff for the world as Sora, Donald and Goofy have now become "Real Heroes" from the constellations, but the reason that Olympus returned to KH3 was that it tied to what happened to Sora back in
Dream Drop Distance when he lost most of his powers from Xehanort during his Mark of Mastery Exam so Sora, Donald and Goofy visit Olympus to get advice from Hercules on how to regain his lost powers, even Nomura revealed in the Ultimania said he felt that Olympus was the perfect world for the "hero's journey" to regain his lost strength, so it made sense as to why it's in KH3. Of course, I wouldn't be too sure if it's going to appear in the later KH games as Hades coming up with a plan to take over Olympus or destroy Hercules is becoming tedious already, besides there is also the issue of Phil not talking due to his Japanese voice actors death.
100 Acre Wood's return to KH3 probably has to do with besides the fact being a relaxing world from the Heartless fighting, it also was tied into what happened to Sora in DDD similar to Olympus, cause Xehanort interfering with Sora's Mark of Mastery caused him to not lose only his powers but also the connections he has with others including Winnie the Pooh. And while to some may not like 100 Acre Wood's story in KH3 it does provide some hints for Sora's Power of Waking especially when Merlin said "Whatever's Lost can be found again", also Sora not on the cover of the book foreshadows his fate at the end of the game when he abused the power of waking to revive Kairi. I think this world could return.
Agrabah could be another Disney world to return to and adapt the events of the third Aladdin film, given that it didn't return to KH3.
I don't think Halloween Town is going to return for the next games as that world hasn't been used in any other KH games since KH2 and 358/2 Days respectively. I also don't think that worlds that have made their KH debut but haven't been making many appearances since then such as The Land of Dragons, Pride Lands and Space Paranoids from KH2, and the Disney Worlds from Dream Drop Distance will be used again for future games. Even Atlantica hasn't been in any game after KH2.
I'm expecting around 3-4 Disney worlds for the next titles, mainly KH4. Regarding the KH3 worlds, I think from the 5 Disney worlds the ones I see the most likely chance of returning are Toy Box and Arendelle as they can have another new adventure with Woody and the Gang with the debuts of Slinky, Bo Peep, Jessie, Bullseye, etc. and Arendelle adapting the events of the 2nd film.
I'm not sure about Monstropolis, Kingdom of Corona and San Fransokyo returning for KH4 or other KH games cause that just comes down to whether Nomura and his team want to continue reusing the world and what story they could tell or just use a new Disney world altogether. I do expect San Fransokyo to be replaced with an Incredibles world.
The Caribbean will all come down to whether they want to reuse it again in KHIV or replace it with another live-action Disney film such as
Jungle Cruise, but I wouldn't be surprised nor opposed of its return to KHIV reenacting the events of the 5th film (
Dead Man Tell No Tales) since I did enjoy the visuals and the world setting in KH3 and the 5th film could be an important plot device to mirror Sora's return.
I'd say from the worlds that are likely to return to KHIV they are:
- Agrabah
- 100 Acre Wood
- Toy Box (From Kingdom Hearts III)
- Arendelle (From Kingdom Hearts III)