The mass market won't remember. Most gamers can't tell you what they played last week much less a decade ago. Collectors will always exist, especially of exotic pieces of gaming culture. I bet you can't even name the most popular postage stamps in the world but last year there were at least 30 stamp sold for over 500k USD at auction and like 4 or 5 that passed the million dollar mark. The marginal utility of money drops as income increases. Rich people dgaf about dropping cash for rare and esoteric items.
It's funny you quote Stamps, as that market is actually on the decline. And so are many other aging collectibles.
Do you think people will pay a premium for Country Western toys in the next decade? Probably not. The people that grew up watching GunSmoke are aging fast, and millennials DGAF about the wild wild west. Western memorabilia is crashing hard right now. Old Train sets? same thing. Kids never played with trains, nor are they enamored with trains.
How many kids from the 16bit era collect for Atari 2600? I don't. And the market for 2600 is also on the decline. Those collectors are in their 50's and 60's now.
We are the kids who grew up with Neo Geo, SNES, Genesis, etc.... Most of us are in our late 30's to 40's and have money. I don't think people will be as rabid for this stuff in 10 years.
This is the general trend for lots of collectible toys. Another example... Matchbox and HotWheels. That market is on the downward slope.
It is a fantastic time to sell 16bit era games. There's probably still some money to squeeze out of them, but it's a terrible time to "invest".