You’re trying to predict what will be sufficiently desirable but unattainable to youth that people trying to re capture that youth in affluent middle age will seek it out.
And then you need to sell at the right time. Look at Raleigh Choppers, they were changing hands for four figures a few years ago, but every 40-something who wanted one has got one now.
Classics like original fat tubed Kleins are still worth less in real terms than they were new so not an investment, and the market for new road bikes is the same as for nostalgia buys, MAMILS, so I can’t see a burgeoning market for old Pinarellos, S-Works etc in years to come.