I'm not sold on the idea that Cold War era cars are destined to become less popular as we all die out.
The cars I lusted after in my youth were not Porsches, and if they had been, they certainly would not have been sub-100 hp bathtubs. Sometimes, a taste for good things is acquired by choking down on some less good things.
We live in the golden age of horsepower, but the cars themselves are increasingly computerized. This will not age any better than the 20 year old desktop computer sitting in your garage did. I suspect young people will treat analog cars much the same way they treat early electric guitars and classic rock music. I've yet to meet anybody under 30 who doesn't love my car. I can assure you that I never felt that way about a Model T.
It may be true that younger people are not after carburetors and distributors, but as more replicas get to be more like cars at the turn of the millennium (one very robust ECU, doing stuff way better than analog ever could), I think the market for loud, proud, and reliable IC-engined retro-mods will flourish as people under 40 tire of a touch-screen for everything.
Rolex and Breitling don't seem to lack for customers for their decades old purely analog watches. I think good cars will stand the test of time.