-co-developed by gamefreak and some other actually competent dev like atlus or level 5
-like persona 4, MC transfers to a new city to attend a university where pokemon battling is the main focus
-protagonists are 20 years old, taller, more mature looking
-dating will be implemented
-MC wears a school uniform
-however can accumulate a wide wardrobe and can change your hairstyle when you aren't attending class
-past characters will return as students and teachers
-takes a more complex turn in terms of gameplay, now revolves around a time-based system, with certain events happening on certain days
-battle system stays the same, trainers will appear behind pokemon still
-pokemon scale is now correct, wailord will tower over every other pokemon for example
-20 years after the events of sun and moon, the city serves as the main hub where most of the game takes place
-but, part of the school's curriculum will have you traveling to different parts of the region to find and battle special facilities in order to obtain "Credits", or badges so to speak
-UBs are back, 20 more are added, play huge part in story in which you frequently enter in and out of their world
just my opinion though. would be cool, but will never happen with game freak still around.