The buzz has worn off
Niantic have created several AR games, I didn't play Pokemon Go but I did play Ingress. I loved playing Ingress in the sense that it made you want to go out and capture the portals etc... Pokemon Go is just the same game with Monsters( Pokemons) instead of portals.
Niantic's success was without doubt due to the uniqueness of the experience but we have now mostly outlived and gone through that period.. On top of that their games become hyper-repetitive after a period of time and one completely loses interest, regardless of how much spicing up they try and do..
I highly doubt that they will ever achieve the same achievements as they did with PG unless of course that design something breathtakingly new ( which is extremely difficult to do).