We don't "need" to visit any world. It's about what worlds they think the buying audience would enjoy playing and inspire them to buy the game more than anything else, and that means popular and lucrative properties will never be off the table.
Again Tartarus you continue to miss the big picture, there are a couple of other Disney animated films (aside from the more relevant films and the upcoming films in the near future (e.g. ) that haven't become worlds that they can utilize in future KH games along with some of the Pixar films now that they join the franchise since KH3.
Going back to my previous post before you refuted it, there is no way that Halloween Town (Nightmare Before Christmas), The Land of Dragons (Mulan), Beast's Castle (Beauty and the Beast), Olympus (Hercules), just to name a few need to return in the next KH game(s) just for the sake of an original story, the popularity that the film has, or how it will look like in the Unreal Engine 4 (which is OBVIOUSLY the main reason why many want Halloween Town to return). Cause again it goes back to whether or not there is anything that they can do with the world in terms of story/gameplay or whether or not it will be in the next beyond the Xehanort Saga and that is the decision by Nomura, the Development team and to an extent Disney.
As far goes as worlds I see returning one last time it's probably Agrabah (Aladdin) and I expect that Arendelle (Frozen), Toy Box (Toy Story) and 100 Acre Wood (Winnie the Pooh) to be in
KHIV.
You can continue "till the cows come home" and refuting your claims but honestly, I already made my point and I'm not benefitting from the conversation I'm having with you Tartarus.
No, I don't think Beast's Castle is impossible to return. Maleficent or some rando original character could curse him again, and then we could finally get a Gaston boss battle. It's not as impossible as it sounds when you consider how they sliced and diced Hercules' plot in 1 and 2, and still found a way to re-enact the original film plot in KH3 regardless.
Did you not see the end credits for KH2? The Beast's fight against Gaston had already happened off-screen when Sora and the gang left the world and the Beast became Human again suggesting that the spell was broken so no I don't think we will be coming back to Beast's Castle again beyond the Xehanort Saga.
Hercules is a different story, because just to clarify to most of you the story did not take place after the movie's events, and going by the story from BBS and the numbered titles (
I-III), BBS and to a degree the first KH game was loosely based on the film's first act when Hercules is training with Phil,
Kingdom Hearts II was based on the films 2nd act (Megara, the Hydra) with elements of the third act (Hercules losing his powers, Herc saving Megara from the Styx and gaining his powers back),
Kingdom Hearts IIIIwas based on the film's third act when Hades releases the Titans to attack Olympus, just minus Meg dying. Even Hades said he put 18 years into the plan to release the Titans from their prison.
The only likely chance of seeing Beast's Castle again is if
Kingdom Hearts: Union X is remade in Unreal Engine 4 for PS4/PS5 which I think it's the closest we'll ever get to a proper Beauty and the Beast world in KH.
Another that seems pretty doubtful of returning is Beast's Castle. Like Birds said, Beast became human and ended the story there. Like Halloween Town, I'm...not as sure what more could be explored with Beast's story. If KH2 wasn't enough, Chi ended its story...again. But ye most of the list still have posibilities. (Like it or not) I kinda can see Atlantica coming back, but odds are a MAJOR time-leap's needed for Atlantica & Caribbean specifically.
Tbh, Ariel was 16 years old during the events of the first KH game, and was 17 during the events of
Kingdom Hearts II, which makes it very unlikely to adapt the entire events of
Return to the Sea.