My main issue is that it's been used so much, It's been in KH 1, COM, KH2, Re:Coded, Days, Dark Road and EVEN the lost KH phone game and I can guarantee you if they weren't focused on the 3 other princesses during BBS, it would've been there too. As much as I find 3D tedious, I am thankful it gave us a break from the world because there's only so much Agrabah I can take.
While Luca and SOUL don't have an actual villain in them (unless we really want Sora to commit more child abuse, he hasn't done enough of that in a hot minute) I think the setting can lean in to more creative heartless designs. Give me a heartless that look like Vespas, or reuse some of the spear lizards from The Caribbean to give the people of Portorosso some justification for their fear of sea monsters, they already look like they'd fit the world anyways. Yeah, KH has been leaning more on heartless for the final bosses of worlds but is that such a bad thing? Would fighting Mother Gothel have had as much impact as the Grim Guardianess? she'd be bascially Maleficent just with a steel dagger and no magic save for Rapunzel's hair. I think it speaks volumes about the team's creativity given the locales they have to work with instead of having to fight X because X is the villain of this world.
I don't know, out of all the Disney worlds that have appeared, Olympus seems to be one of Nomura's favorites and he'll use ANY excuse to shoehorn it into the plot even if it doesn't make any sense. Need I remind you of the hero's theme that plays in Country of the Musketeers in KH3D? a game where we were so close to going without any nods to that world? Nomura might make up an excuse and say Sora lost his car keys there and necessitate a whole *#@ visit JUST for that. What I want to see is worlds that haven't been featured as much as others, namely those that we've visited 3 times or less in the series as a whole. So that would leave both Olympus and Agrabah out of the running and give us more stories with worlds like Neverland and I guess Beast's Castle if Nomura gets drunk and covers Belle's Magical World. You heard that right, I'd be desperate enough to want a POORLY MADE DISNEY DIRECT TO DVD SEQUEL over Agrabah and Olympus.
I'm honestly hoping that this is a joke on your part, because I absolutely dread having to go there again. I already had to go through the world in KH3 five times because I wanted to get Oblivion for the secret boss, and each visit to that damn world was always the first chance I got because I wanted it over and done with.