Gonna spare you guys of the fake leak faggotry setup and just post the points:

-Next game is Y-Sword and X-Shield set in Kalos after the events of XY.
-Goes into the lore of a past war between Kalos and Galar. AZ will be back.
-Kalos being vaguely shield shaped was not intentional orginally but Galar was purposely made to be a sword shape.
-Game will see the return of Megas in gen 8. There will be a Mega vs Dynamax theme where you use your Mega to face Dynamaxed
antagonists' Pokemon at various points.
-New megas for a bunch of Kalos Pokemon including starters. Gamefreak already had a bunch of design ideas for them but originally
didn't want Megas for the new Pokemon cause people weren't familiar with them yet. Saved for when they revisited the region.
-Many of the gym leaders are swapped out. Game will feel like a new experience and story in a familiar region.

How likely is something like this? Who knows. They're on the Switch now so whatever game they make is gonna take more work.
Its probably easier to do a kalos game since it was 3d than build up from nothing for D/P remakes. Kalos fits the general feel of this gen
while Sinnoh is one of the Japan regions. People reach for ways to make it work in fake leaks cause its next in line. This is not a leak, don't dig this up in a year.