The idea that Mega Evolution is being removed is incredibly ludicrous. It was hyped up a lot, it's popular, and it brought a significant change to battling that you don't just remove.
The worst thing I see happening is GF not releasing any new Megas this Gen and restrict access to it so it's postgame only.
Megas disappearing altogether would definitely be odd,not to deny they have been straight up centralising.
From the beginning of gen6 the comp community were deciding which megas were
too overpowered,and which ones were simply overpowered:
MegaKangaskhan massacred teams with its bulk,good speed and broken ability alone;
Nothing could stand up to a MegaMawile after a single Swords Dance with its huge power ability + base 100 attack stat,and its typing meant easy setups if you didn't have one of its three counters;
MegaGengar could revenge kill anything the player wanted for the overwhelming benefit of its team,using perish song + shadow tag to take out the defensive walls its absurd special attack couldn't knock down.
MegaGardevoir ,whilst never banned, got base 100 speed and a 165 sp.atk stat,combined with the ability and coverage that allows it to pulverise anything in two hits.
A significant change to battling indeed - it meant that if a pokemon wasn't in a mega form,it was often only there to check other mega forms,or clear the way for the mega to sweep.
New
forms as opposed to evolution, have in the past meant altered stats,typing and abilities in Rotom and Meowstick,for example,and these are also the main beneficial qualities of a mega evolution, only with a sense of balance in mind, and no restriction to one per team.
The irony that you could finally use beedril or charizard in a serious competitive battle,but not beedril AND charizard! With new forms,this is now possible,with new megas we just push standard pokemon into further redundancy.