I think the “problem” is twofold: 1) phones are too much 2) too many books
1: using a book used to be easier than computer. You had to turn it on, wait, sit in a chair. With book it’s just grab and start reading in any position. People were/are reading standing up in Moscow metro. Computer was also limited in what you can do with it: I had a few games, a few programms and if I wanted more, it’s either going to a store for CD or using a slow Dial-up (check if no one is talking on the phone or expecting a call). With smartphone now there is Youtube, games and a ton of text that talks back to you (like HN or Twitter).
2: I find that many books and movies just say too much. I went out of the movie theater from Hellboy reboot when they started explaining the lore right away. I don’t mind a bit of exposition, but a film is not the right medium imo. Similarly with books: I feel like at least some of them could be a series of Substack posts if not Twitter threads.
So I agree that books are dying out a bit, but I’m optimistic that they are being replaced with mediums more suitable for the message. Also I hope there will be more specialized gadgets like ReMarkable tabled that you can’t do everything with.