It'll be interesting to see how different players define these terms.
For me, unless you go back a very long time, "vintage" and "classic" are fairly synonymous. And so much "modern" music has been made on old instruments, or old-style instruments, that I'm not even sure what that term means! A guy like Dave Grohl, who's playing some pretty meaty stuff, is playing a Trini Lopez model Gibson these days, that came out in 1964! And he also uses other old-style instruments. This is just an example, of course. But we can all think of dozens of modern players in this category.
I get that metal is different, and has a different instrumental/pickup/amp vocabulary than other genres, but it's been around a long time, too, in one form or another.
The active EMG pickup was introduced when, late 70s? I know Steinberger was using them in the early 80s, because I was interested in one at the time. But the thing is, that was over 30 years ago. Does that make it vintage, classic, or modern?
Last year, my son did a short tour with The Academy Is, a well known punk/emo band. He played a Tele and a 335. They weren't hot-rodded new models, they both dated from the 80s and had standard pickups. I have no idea what he played through, I've forgotten, but I'll guess a Mesa. So is that stuff vintage, classic, modern, what?
So I'm copping out. Can't answer the question. LOL