Maybe.
I don't honestly expect them to introduce Mega-Evolution in the game until 2019 at the earliest, but one of my goals in the game is to have a Male and Female (if applicable) Pokémon of each species that is a 100% IV, so that means I am catching any Pokémon that could potentially Mega Evolve. I'm only keeping the best of them, but those "Bests" could be absolute beasts under Mega Evolution.
Okay, maybe not "Absolute beasts", but could be "Viable Pokémon to use in Raids, under Specific Circumstances, like a Mega Pigeot vs a Machamp or a Mega Absol vs non-Focus Blast Alakazam or Gengar" sort of useful way.