When it comes to the stuff from the last 30-40 years, it's hard to tell what will endure. Like I've said, I do believe Eddie Van Halen will be remembered for his contribution to the guitar. Nirvana will probably be remembered for ushering in Grunge, and since Cobain died so young it puts him in a different category than he otherwise would have been in. But really, only time will tell. Going a bit further back, I believe the music of the Beatles will endure long into the future, possibly indefinitely.