As of lately I am seeing model cars that used to be carried everywhere have disappeared from most store shelves, Wal-mart no longer carries them, same for K-mart, Target, Toys R Us, None of them, only place in town that still has them are Ben franklin and hobby lobby. I also think any of the American Chopper model bikes and other such stuff will be worth a fortune, Anything with a huge fan-base. The O.C.C. and W.C.C. choppers should be good in the future, I think those re-pop Schwinn Phantoms will be good. Anything too expensive for the average Joe to get cheap.
I have a big Richard Petty collection, when he dies, god forbid, I'd be set for life. I had a huge Earnhardt Sr. collection too, but when he died people went nuts and I sold a lot of it. (I'd have been stupid not to at those prices) Also have Earnhardt Jr. stuff too from before his number change that will be worth more in 50 years.