Well since Ti doesn't fatique, rust, or scratch, ALL of them will be classics. If they are re-built with new components every coupla decades, they could all still be in use 1000 years from now. Most steel bikes( and aluminum, and especially carbon fibre) bikes will have long since deteriourated to nothing in a few decades. You could literally leave a ti bike out side for hundreds of years and the frame should be good as new.