Ok so random unfocused thoughts, hopes and predictions:
-Calling it now: PLA-style mishmash starter trio but instead of regional forms they get Megas. So, for example, Mega Serperior, Cinderace and Empoleon. I just came up with that trio from the top of my head, feel free to theorycraft your own.
-People seem sort of mixed on the idea of a whole game being heavily centered around if not entirely set within one city but honestly I think it sounds insanely cool. Pokemon's aesthetics for me at their best when they show settlements where people and Pokemon cooperate, I loved looking at pictures and videos of the building interiors in SV and especially Indigo Disk for this exact reason. A whole game going in on this by design is exactly what I'm looking for, and its a premise that suits Lumiose more than anywhere else in the Pokemon world other than Castelia.
-That said, I REALLY hope this is set in modern day after XY. The trailer look does not correspond at all with an old-timey 1800s aesthetic like I've seen some speculate, and really I just want there to be an emphasis on the "retroactive sequel" element. This is what intrigued me most about the idea of a BW3, going back to this old region after a long passage of time to see how everyone's doing. I NEED adult Emma. Please.
-So I guess Indigo Disk really was "The Return To Unova" and that's that. Honestly, totally fine with this. You guys still got a whole new setting with unique mechanics, characters and worldbuilding together with some really nice 3D map design and a great set of bosses and minibosses! That's a more meaningful addition to the region than any ILCA rethread ever could've provided.
-So obviously Zygarde's gonna play a big role, probably with a Lumiose-wide cell hunting quest, but what about the other Kalos legends and mythicals? I could see Volcanion as a PLA save bonus, Diancie for SV, Hoopa not being dependent on owning another game and Eternal Floette as a special in-game gift for some major milestone (Beating a postgame superboss? Dex completion?)
I have seen people very happy to see the 2025 release date, but if it happens early on the year then the dev cycle would not have improved at all since LA came out in January.
Good news: When PLA was revealed iirc it already said "Early 2022". This is just 2025. Also noteworthy that there's no gameplay footage, tells me that they are not gonna show more until they're ready.