Every bike that I have sold(Tempo, Super Sport, PFN10, Gitane Super Corsa, Davidson Impulse, Alpina 5.5, etc.)has been bought by a young man in his twenties. I think their will continue to be a good market for vintage steel with a slow gradual rise in prices for rider grade bikes.

Collector grade bikes may tend to reach a plateau. When they go over $1,000 they compete with a lot of other toys. They may keep pace with inflation.