>>53187753They seem to be committed to introducing and discarding a new gimmick in every generation now, so I doubt they're going to rehas megas any more than they're going to bring back G-max or Z-moves.
Mega evolution is sort of different from the others, though, in a way that makes me think the original plan was to make it an ongoing mechanic in future gens, like how gen 3 introduced abilities. Firstly, all other generation gimmicks are tied to the specific region the game takes place in; in case of gen 9 the material to make tera orbs comes from Area Zero and terastal energy as a whole is implied to be connected to the unknown legendary mentioned in Heath's book and the professor's notes, so it makes sense that you don't see it in other regions. Megas however show up in two completely different regions, one based on France and another on an area of Japan. ORAS also establishes that gen 6 (and by extension all subsequent games) take place in a separate timeline from the earlier gens, differentiated by the presence of mega evolutions. It seems rather odd if they decided to split the game timeline in two just for the same of a one-off gimmick, which also suggests to me that it was originally intended to be a returning feature in later games.
