Just like classic cars, interest in the older vehicles will wane and newer cars will fall into 'classic' status. I think in recent years, there is more interest in older MTB's. A lot of collectors grew up when MTB's were dominating the market, from the mid 80's to the mid 90's. My bikes are all from '85 to '97. I should be the prime audience for an older MTB, but I just don't find them attractive.