Metal doesn't get killed, the people that listen to it grow up.
I guess it matters what age you are as to what Metal really is classified as:
In the 80's: it was Maiden, Metallica, Ozzy, Guns n' Roses, and everything with an electric guitar. I exclude Hair Bands out of the Metal category, because that shit ain't metal. Metal to me is Slayer, Obituary, Morbid Angel, all that badass shit. Before cd's!! Ya, I'm 33 fuck you.
90's: Everything that didn't fit into a marketable box, they called it Metal....
Grunge took over for a bit, and then fell off as the next hottest thing.
Pantera helped bring back metal by mowing everyone's faces off.
Korn was revolutionary (1st two albums, that's it) They single handledly brought 7 strings back (not you Steve Vai) and actually had a new sound......same as Nirvana having an actual new sound.
Then shit got cookie cutter:
Everything sucks nowadays because kids just play guitar hero and think that they can play guitar so they start a band and make shit noise. Except for the likes of Mastadon, Slipknot, Black Dalhia, Dillinger Escape Plan, and a few others.
Just a few gems off the top of my head from back in the day - we'll probably never have the pleasure of hearing supreme bands like this:
Faith No More, Alice in Chains, STP, Helmet, Tool, Rage, Primus, and others I can't remember right now.