I can guarantee you there are collectors out there stashing away NIB (insert brand and model of polymer semiautomatic pistols here). Eventually, they will no longer be made with their current specific features and a future buyer will get the "gotta have it" bug and pay extra money for one, or they want a "birth year" gun, or will have some other reason to want it.
Of course companies sometimes come up with plastic guns that seem pretty collectible for various reasons - the recent ex-US military Sig-Sauer M17s come to mind.
On the surface it seems easy to discount these non all wood and steel guns as future collectibles, but common NIB guns eventually go up in value. And they are still guns with intrinsic utility, not Beanie Babies or Pet Rocks.
