My husband has been watching lots of the videos from the Glastonbury festival over the last couple of days. There have been some great performances, and lots of online chatter about many of them. But it really struck me how many of the groups that you heard about everywhere were all old. Foo Fighters, Guns 'n' Roses, Elton John, Rick Astley... I could go on.
I feel this phenomenon happening as well. 25 years ago, I was in a niche band, and we were super happy to be paid in beer money. There wasn't a niche market for us that could be lucrative in any sense, but today there are loads of niches for musicians.
The other thing you rightfully point out is that we no longer have quite the same shared culture we once did. This adds to the fragmentation our society faces, but it's in the service of more choices for consumers, and more opportunities for artists (like us!).