It's mostly nostalgia that drives these things - it's people remembering, "my first X", especially when X was some new exciting thing that didn't exist before. Think about the current collecting craze for "retro" home computers - especially if they still have their original box - sometimes the cardboard box is worth more than the electronics inside!
What's genuinely new in radio control models these last twenty years? Most things are just incremental improvements, and the only really 'new' thing has been multirotors. So perhaps things like an original DJI Phantom will be collectable - especially because most of them will have been crashed, flown away, or worn out - that makes the few surviving ones more valuable. If you still have one in really great condition, and especially if you still have the box, now is the time to pack it away safely, ready to sell to some keen collector twenty years from now.
Another new thing, though perhaps not as exciting, were the first 2.4GHz systems. I can imagine future collectors with the first models of Spektrum transmitters and receivers inside a display case.
Most of us are getting pretty old, so if anyone is likely to make any money, it's more likely to be those who inherit our junk! The danger, of course, is that it will be tossed in a skip, because whoever has to deal with it won't be able to identify those few valuable items amongst the piles of stuff that are genuinely worthless!
