re: What Metal band did Nirvana/Grunge kill in 1991 that was going to hit next?

Winger, Firehouse, Slaughter, Warrant, Mr. Big, and Skid Row were the main early 90's hair bands I remember. All of them were kinda popular right when grunge hit. But at that time I think kids were tired of hair metal in general.

It's hard to say who "started" a genre of music, but often times Pixies are credited with "starting" grunge in 1986. However, there were other bands of similar styles prior to Pixies like Scratch Acid who formed in 1982 in Austin, TX. And across the pond in England you had "Gang of Four." (Cobain admitted he was influenced by both Scratch Acid and Gang of Four).

The Pixies's lead singer admitted he was influenced by Husker Du. The Pixies' guitarist said he loved Black Flag as well as Gang of Four (so both Pixies and Nirvana were influenced by Gang of Four).