I think fiction is going to move more and more towards the web novel model, where extremely long stories are published on a chapter by chapter basis. It has a far higher chance of attracting new readers, because new stuff is constantly happening surrounding the work.
Music is the same; there was a time when your record company would pay for studio time, mastering, publicity, etc. Today? If you’re a serious artist you’re just expected to have $10k in recording gear and the knowledge of Logic Pro to produce your own songs and run a Twitch/Twitter/insta/tiktok account to connect with your fans. You honestly don’t even need a record company anymore since you can book a tour off Spotify listener count alone (touring is where the money in music is these days).
So what are publishers doing in return for the higher sales price of ebooks?
And ebooks generally are cheaper; there’s a ton of $0.99 genre fiction available on Amazon.
From the outside it looks like they operate more like VCs, publish lots of books, see what sticks.