For me it's less about the relatively to the year we are in and more to when printing processes changed I'd say anytime pre1975 is safe to be vintage late 70s still feels a bit more modern. 1980, even though it's almost 40 years old already, will never be vintage in my mind. Vintage for cards for me is more process related than age.
I'm not sure if all states do this but Connecticut has a "classic car" license plate. If a car is 20years old, I think that's the cut off, someone can pay the price for the designation and put a "classic car license plate on their car. It's kinda cool for a 50's Chevy Bel Air, not so cool when some yutz puts it on a 91 Honda...which I have seen.
Maybe I just have a hard time imagining the era i grew up in being vintage or classic...
Depends who you ask. I have been calling 1973 the cutoff. The last year Topps issued cards in several series. The line doesn't move relative to the current year. But I prefer the way comics define eras, Platinum/Gold/Silver/Bronze/Modern (aka Chromium) Ages and so on. Lets you draw lines at fairly-well-agreed years/events that don't need redefinition every decade.