Well, pretty much everyone I know who "camps" with their kids is rockin a TT of some sort. Most are newer and pretty big. We got sucked into RV camping from tent camping because of a move to AK and a little more extreme environment than the National Park campground. Nevertheless, it stuck, and we enjoy the camper.
If sales are slowing, it's becasue of market saturation, IMO.
IDK the actual numbers, but having just taken a road trip down to Vegas and back, there are more freakin Rv dealers than I could imagine. Same with driving east from here. Same in the Midwest....etc etc.
Guessing that many existing dealers have exploded with the last economic boom and plenty of new dealers as well. Bound to be some leveling of the industry.
It's not like everyone needs a rv like they need an I phone.