I think metal is a race for its life: to escape being a mainstream genre.
Hardcore was brilliant in that it deconstructed the rock/blues paradigm; but from deconstruction, we must reconstruct.
Classical music is too far an extreme, but Dead Can Dance/Tangerine Dream/Fripp & Eno territory is where metal should go, and its best bands like Morbid Angel, Burzum and Demilich reach that level.
But it can be pushed further.
Metal is not counterculture; it is counter-counterculture, as Black Sabbath made clear. The hippies aren't going to save us. We need to get back to reality, only death is real.
As long as the music is too easily imitated, however, it will be assimilated by rock music.
I used to believe in rock, blues and jazz as some new invention; then I heard some Norwegian, Swedish, German and Scotts-Irish folk music from the past 200 years and realized that actually, these guys did everything the blues did centuries before, and did it better.
Like metal, a forgotten but better history of humanity...