Then, very briefly, the technology of recording music developed to the point where it was commercially viable to mass-market music. As happens with any technological revolution, that triggered a massive spike in innovation. That spike lasted ~50 years, we're just getting to the end of it.
My point is that what happened between ~1950 and ~2000 isn't normal. That's not how fast music normally changes. That was a specific response to a specific stimulus. It will take another stimulus of equal magnitude to provoke a similar level of change.
(also: musicians were almost permanently broke prior to the recording industry. Interesting, and sad, to see that returning too)