Somehow I very much doubt it.
Mega Evolutions had a very big problem, which was this – only a fairly small number of species has Mega Evolutions - and while digivolving Pokémon certainly breathed new life into some particular species that genuinely needed a boost (indeed, the loss of the likes of Mega Mawile and Mega Beedrill is still, frankly, woefully lamented.... and the loss of the horribly-broken-at-the-time Mega Kangaskhan was celebrated by certain meta crowds but that's neither here nor there), it was still an exclusive gimmick that only applied to a few lucky Pokémon rather than to all of them.
Note the recurring theme of all gimmicks since Mega Evolution: Z-moves, Dynamax/Gigantamax, Terastalization. What do they all have in common? Every single Pokémon, regardless of its level or state of evolution or belonging to a special line or not can use them as a baseline. Of course, every one of these gimmicks has its few special moves or forms that only apply to a few species – but that's on top of the basic gimmick usable by every Pokémon.
Don't get me wrong, I definitely miss certain mega evolutions – but I strongly suspect that Gen X, whenever it happens, will have a whole new pointless rule-of-cool gimmick, the current gimmick will be consigned to history with other previous generation gimmicks, and Megas will probably only rear their heads again when Kalos gets a remake... which is a terrifying thought in and of itself. >>;