Give me one iota of proof that megas are still in. In all the reveals, all the hype train, we have not seen a single mega.The protagonists do not have a Mega Ring, only a Z-Ring (or whatever they're calling it) for Z-Moves. Furthermore, in XY multiple characters said mega evolution was a new thing exclusive to Kalos. (ORAS can be excused since it was same-gen.)

If your proof is, "It's a new feature, game freak would never remove it!" then see the following:
>VS Seeker
>Pokewalker
>following pokemon
>emerald battle frontier
>seasons
>Pokeradar
>PWT
>difficulty settings
>gym leader rematches
etc. etc. etc.