Actually, I don't think MP3s will have much of an impact on the parts of the music industry that should survive.
Basically, rock music was a gimme. Cheap and easy to produce, all hype and no substance, just like the blues, another invention. Want the proof? It's written in western scales and western tuning, derived from the pentatonics of Celtic folk music, and the syncopation of waltz drummers. The blues is a farce. Rock is a farce.
So there was big profit for many years and now it comes to an end... who cares?
People are still going to buy bands on par with Demilich, and they're still going to buy classical. That Pantera, pop, rock, jazz, blues and hipster electronica die out is no trouble to me... in fact, it's victory.