Alas, I know this and it makes Sister Mary want to go 'bleech'.... No, wait, that's another play entirely.
Go get your copy of The Season by William Goldman. At the end of the chapter on Hair, a producer is asked what the success of Hair would mean for Broadway. The reply, "I think we're in for a spate of sh*tty rock musicals." I quoted that after I saw Mamma Mia.
Things don't change very much: Elvis, The Beach Boys, John Lennon. What's next?
Good Lord. What IS next?
"If my life weren't funny, it would just be true. And that would be unacceptable."
--Carrie Fisher