I remember last July and the launch of Pokemon Go. It was a big deal for my son and I and over the few weeks after it certainly got more popular in our house as my wife started playing as well.
A few month later though and the popularity has definitely waned. For my son and I the game is still fun, but while living in an area with very cold winters (Alberta, Canada), we do not walk nearly as much now.
A very interesting study came out related to exercise and Pokemon Go that I believe is a microcosm of any kind of exercise change.
How Pokemon Go Increased Exercise in 2016
When Pokemon Go was released the idea was that people from everywhere would increase their walking to go to Pokestops and to find Pokemon in the wild. In our house it initially led to walking, then to bike riding to cover more distance, and finally for my son and I we would go for walks in more urban areas like Calgary.
I suspect that for many people the game was initially exciting and then after a few weeks they reached a tougher level and just gave up the game.