Sounds like the phenomenon of "Top 1% owns 99%" is impacting music as well as wealth, but it that purely an American phenomenon? The concentration does not seem to be as bad in UK or Europe, or here in Australia.
As an old fart (punched card Fortran guy) it seems to me that most pop music has become very homogeneous there; the same four chords and riffs over and over with autotuned well-known-female-voice over the top.
Listening to random classics on Youtube (today: The Monkeys, The Stranglers) the difference in texture and nuance from then to now is very evident.
It will be interesting to see how AI generated music goes:
a. Will it be indistinguishable from human output, or is there some 'human' quality that WE will always be able to detect?
b. What music will an artificial consciousness prefer? Jazz? Human au Naturale? - we may be surprised!
[Personal Taste warning]
There is some 'real music' still coming out of USA, but mostly in genres ignored by the Mu$ic Indu$try, My favourite is Jackie Evancho who seems to have been blackballed by the industry since singing at Trumps Inauguration, but her vocals are very impressive (and very human) to my ears.
[/End Personal Taste warning]