That is not what is happening? There are soo many niches and subgenres these days, and it is evolving year over year.

Did you miss a /s? There is more varied music being created every day than ever before right now. There are sub sub sub genres you can seek out if you want. Contrast this with when I was a kid and we basically had what the radio played or what cassette we could buy with our $10.

The problem now is that we have so much content (music, books, movies, short vids, long vids, etc...), and not enough aggregate time to consume it all.