The blockchain solves a big problem for distributers: it makes DRM attractive. I don't necessarily see the case for textbooks catching on with consumers easily, but in other industries, like film, having the NFT "collectible" version of the item is attractive to some consumers. Of course the DRM protections could likely be trivially bypassed, but consumers could more easily make back a return on their original purchase after they're done with an item, and for collectibles, could display these purchases for others to see. This incentivizes the consumer to desire the DRM-protected item over the off chain asset. The film industry has already begun to explore this with distribution platforms such as https://vuele.io . Definitely not in support of it, but it seems a logical way for blockchain tech to be adopted into these industries.
It's interesting how little this is talked about. In the case of something like Vuele, they don't need to have an external database (the blockchain) for their concept to work. They could allow Vuele accounts to trade ownership of download rights and set up a marketplace for people to buy and sell.
But given the option to buy the right to download Zero Contact from some Vuele user or buy the download from the Apple store, why would anyone choose Vuele?
I think the bet on NFTs is that enough people will buy into the concept that it will legitimize itself. No one would want to go out of their way to buy movies from Vuele but if NFTs were to become popular enough people may be willing to buy movies from popular NFT marketplaces like Opensea, which they may already be buying other things from.
The initial impetus is dependent on people having an innate desire for scarcity. It's not solely about speculation. If you tell people they can be one of twenty people to own the original Vuele copy of Zero Contact there are going to be some buyers.