Everyone agrees that it's bad. Doesn't stop it from happening.
Mega Ampharos was part of the first megas revealed, and it did have a type change. (This also doesn't really have anything to do with whether Game Freak would keep in Megas or old Pokemon...)
I think its like we had in Alola...
In UltraSun&Moon we got redemption.
The same will be here and maybe they will add some new megas and Z-moves. Mega-shield Blastoise and Mega-sword Venusaur coming. Kings Sword and Queens Shield or RoyalSword&Shield or GigantaSword&Shield or however they will call them.
You all are too pesymitic.