I don't know about it all disappearing, but it's already starting to decline a bit over what it was a few years ago. It'll never disappear, not as long as we have MTV glorifying all these no talent shits that think you can just pick up instruments and make millions.....................
Look at the shit out today..... Trivium, BFMV, As I'm Gay Crying.......... That's MUSIC!!!! Well, according to some............ And as long as there is a market to push this kind of lame ass shit on, it will never die............
As far as rap goes, it's about the same. As long as people are listening, it will never die.