I can see how trails is fading, but could it also be a regional thing? If you think of the amount of development in NJ an eastern PA that's happened since the 80s, a lot of space has disappeared.
My friends and I had a small spot right on my street as a kid. Hell, I remember my friends little brother would even ride on his mustache handle bar banana seat monster and still have fun just rolling over stuff. Anyway, we had a small spot in the woods right across the street from a friends house behind some neglected private tennis courts. Now that spot is a mc mansion.
If you think of how much little available land there is now compared to then, there's a fraction of the space, legal (or not haha!).
Add in the advent of the Xbox and gaming and now kids are more into sitting inside versus getting out. That's a whole other discussion.
But I will say, when I take my kids to the local park here in town, the skatepark is always packed with skaters and bikes. That is promising. If we get in more pump tracks in local spots that are legal and open to all like Alexandria and what is starting up in west Milford, skatepark kids will probably start picking up shovels if they have the time between soccer, hockey, baseball and trying to be the next valedictorian of their elementary school.