Trends are always kind of funny. At some point, someone is going to look back 10 years from now at someone dressed up like Fonzie & Bettie Page and get a good laugh. Kind of the same reaction you get when you see a guy with a mullet standing next to a teal green mini truck with a pink heartbeat stripe running down the side.
I guess it's usually the extremes that come and go quickly. The classics that are pure and not meant to be anything than what they are usually have the longest shelf life. As long as you don't get all hung up on stuff and just have a good time with whatever's the latest craze it really doesn't matter.
So much of it all depends heavily on who's in their 30s-50s with new found disposable income. That seems to be what drives the trends in the collectibles market anyway. Must....revisit....glory....days.