I think Quadratum could be a prologue world, just like Destiny Islands or Twilight Town. Based on what we got, the look and feel of the ending of that teaser with Donald, Goofy (and Hades?) is more fantastical like previous games.
I don't think Disney would allow a game in the main series with no Disney worlds. A world/planet based on Star Wars I could see happening. It has more iconic and unique settings than Marvel. I'm not sure if a Marvel world (aside from Big Hero 6) would fit. Would it be based on the comics or movies? I could see some heroes appear as summons or something. 'Guardians of the Galaxy' would fit with the gummy ship missions, even though I'm not a Guardians fan.
Kingdom Hearts 4 looks good, but I get the impression the whole game is going to take place in that realistic city (as in, no Disney worlds), and I really hope that I'm wrong.
I don't think Disney would allow a game in the main series with no Disney worlds. A world/planet based on Star Wars I could see happening. It has more iconic and unique settings than Marvel. I'm not sure if a Marvel world (aside from Big Hero 6) would fit. Would it be based on the comics or movies? I could see some heroes appear as summons or something. 'Guardians of the Galaxy' would fit with the gummy ship missions, even though I'm not a Guardians fan.