20-Year Prospect
There was a time when your biggest worry as a camp counselor was outrunning that maniac in the hockey mask. Different time, the '80s. Now, you have to contend with all the other amusements clamoring for attention.
Still, there's absolutely no sign of any slowing down in the desirability of the position. While the bulk of the available opportunities are seasonl—and that season is summer—there are some full-time positions and the number of them is keeping up with other fields (source).
No matter how much technology advances in the next twenty years, they're not going to be able to simulate wilderness. Later on? Sure. They might have to with the havoc of climate change. But for now, there are woods, lakes, nature paths, hungry bears, really everything you could want at camp.
If you're lucky enough to find one of the (again) extremely limited full-time camp counseling careers, it could be something you stick with for a long time. Canoeing, friendship bracelets, and tire swings never go completely out of style.