>X and Y obviously were in the Mega timeline
>Pokemon Origins had Mega Evolution
>Ore Ass were Hoenn in the Mega Timeline
>No Johto, Sinnoh, or Unova stories yet
So, the next remakes are going to be either Johto, Sinnoh, or Unova.
We won't see anymore remakes for at least another 4-5 years. Who knows if gen 7 will even bother keeping Megas, though it is very likely since they've kept up with everyone else's forms. Even so, megas will probably die down a bit.
And besides, the next remake will obviously be