Ted Gioia's Is Old Music Killing New Music? is wonderful. (And Ted Gioia is wonderful, and the newsletter is wonderful.) The best introduction to the piece is the introduction of the piece itself (it's just a click away!).
Its main explicandum (the "death" of new music) is a few facts: in 2021, we collectively listened to more old music and less new music than in 2020, not only in terms of share but in absolute terms.
Ted expertly analyzes the decline of new music. But I'm interested in the title question, which he doesn't really answer. In whatever sense new music is dying, is it old music that's killing it?
I'm tempted by this line of reasoning: 1. Music benefits a lot from being a focal experience (or at least from being really famous). 1. We have fewer focal experiences than we used to. It's harder for art to get really famous. 1. So you'd expect new music to get less popular. 1. But old things' focality doesn't go away (at least not quickly), and neither does the human desire to enjoy music that changes the world (or, at least, music that is A Big Thing). 1. So new music gets a bit less popular, and old music steps in to fill the void.
Meanwhile, the difficulty of making a big cultural impact with music changes how it is supplied (here are some brief thoughts from Tyler Cowen on that subject).
There are, over time, fewer of us who lived through a certain kind of mass culture. It can feel gauche to say that one thing you want from music, at least sometimes, is the feeling that many millions of other people have also been moved by it. But a lot of us do want that. One often hears about "fragmentation," algorithmic pigeonholing, and so on: mass culture is turning to shards. In analyzing the precise shapes of the shards, we can miss the simple fact that the former whole is gone.