I get what you mean. Vintage watches are all the hype now and hence command a premium. Whether the market momentum will continue with the same pace, is really a wild guess.
I think it depends on the watch. Right now stainless steel sports watches especially chronographs are in right now. This can change as fashions change. Some people sound just like the people that said housing prices would never go down when talking about the prices of vintage watches. I'm just glad I like gold platinum and palladium watches the most.