I think the question is whether vintage and classic is an era like the Muscle Car Era or is it a floating demarcation point in time or is it a set of common features exclusive of others?

For me, my opinion, classic and vintage is a fixed period, an era, that ended when aero cables, or God help us, ughhhh, brifters came into being much less anything carbon fiber. No matter how long into the future we extrapolate such bicycles they will never be vintage or classic.

Or about 1986 plus or minus a couple of solar cycles.

J