[Yodel0914]

One of the interesting things about music since the advent of streaming is that it's far less segregated by time of release. Anecdotally, I know 18yo kids into metal who are as likely to listen to Metallica or AC/DC as they are a current-generation metal artist. I don't think there's anywhere near as much of a currency bias as there was ~30 years ago.

More anecdotes: the crowds at metal shows I've been to are quite diverse age-wise - from ~15 to ~65. The demographics don't seem to change that much with the band playing, except that that's less older people for the really heavy bands (Cattle Decapitation comes to mind).