To that, I'd respond "scarcity."
It's hard to imagine highly valued art (either culturally or monetarily) without scarcity.
Consequently, I expect the next few decades will see similar progressions to the past, when technology encroached on scarcity (e.g. painting after the photograph, live performance after consumer video/music playback).
Scarcity will reestablish itself in whatever guise remains technically feasible, and again become valued.
In the case of LLMs and diffusion, I expect it will be creating things that are so novel they could not have come from AI.
Hopefully skillful, deep parody and the absurd will reassert themselves, as post-JS-Daily-Show I think that's been missing in culture.
But it sure as shit isn't generic pop music, which will be the first thing to be churned out of humanless hit factories and flood the market.