You can guarantee there will be items just about to be made any minute that will be future collectables. Just what they are is to be revealed at the right time. It's often things that were commonly disposed of once, that reach the right time to becoming sought after collectables.
For instance, who would have guessed that plastic Tupperware dating from the 1950s could become valuable later on??
Some lucky speculators can hit the jackpot in advance by holding on to the right items, but, by and large, that is prone to failure as everyone else thinks the same thing. Lady Di 50c piece anyone?