Developer Niantic on their blog after receiving a BAFTA (British Academy of Film, Television and Arts) award for Best Mobile and Handheld Game for Pokemon GO that their title had 65 million active users every month.
The fact that Pokemon GO is still having this big of an audience, nearly a year after it released is incredible. Especially since a lot of people considered it a fad, one that did indeed die down after initial release when it seemed like almost everyone was playing it. Yet, despite certain lows, the players kept coming back. Whether it was because of desire, or the new Johto Pokemon, or various other reasons, this is very impressive.
Niantic promises that the game in the Spring will have “all new cooperative social gameplay experiences in Pokémon GO that will give Trainers new and exciting reasons to get back into the sunshine.”
So it would seem that players will have a reason to come and play Pokemon GO for quite some time.