I stand by my theory that the secret ending is actually a teaser for DLC, not a new game. (SPOILER)Plus, pretty sure it teased two worlds: one for Verum Rex, and one for TWEWY, since it was specifically the 104 building (not any other variant of the IRL 109) that was shown front and venter.

(SPOILER)I am really interested where they're going with Luxu and the Foretellers, though. With all that build up with Back Cover and Union X, I really didn't expect them to end up as antagonists, which it looks like it's going to end up as. Also, calling it now: Sora is the Master of Masters.