You should see what planet fitness did to the small gyms in my area. whoo000o
In my area it didn't hurt much. Snap Fitness came to town and there's still several small gyms doing well.
The small gym half a mile from here is still going...the Fitness Center USA and the Planet Fitness that opened to compete are not. The former FC USA is now gone (torn down to build a CVS), the former Planet Fitness is a computer repair shop.