The nation is becoming more urban - and urban raised folks find real camping scary.
That stops many young families from getting into camping. Another factor is two working parent families often don't have two days off each weekend. Harder to work a weekend camping trip into the schedule.
We all know how the teenage years, school activities, sports, etc - can pretty much bring camping to a stop with no free weekends.
Every year the Texas State Parks folks go out to fairs, community events, etc - and one factor they find is that to most people going to a 'State Park' is considered to be something like going to Six Flags or Schlitterbahan. Going out to enjoy nature doesn't enter their minds as a possibility.
We need young families, young people, to get interested in camping and RVing. The costs of entry level RVs certainly doesn't help get more folks involved.
That young couple, young family you see at the campground might need some help learning how very much fun camping can be. How friendly other campers/ RVs are.
If the market starts to dry up, the number of places open to us old farts will also decrease.