Game Freak will likely continue to make handheld mainline games since they print money for Nintendo. But as for mobile, I could see Pokémon GO constantly updated with new Pokémon from later generations to keep the game fresh.People are talking about this at work. This game is a casual juggernaut.
Will be interesting to see the future of Pokemon now that the whole JRPG structure of the series has proven itself both irrelevant and potentially constraining to its appeal and ability to generate cash.