True, but I expect the critical mass of the target group will remain to be people frequently listening to Audiobooks --> Those people are more-likely subscribed to an Audiobook service --> are not paying a per-audiobook price but a flat-fee --> The flat-fee for the whole catalog is lower than buying one audiobook.

I would expect this target-group to access a mix of human and digitally narrated books during the transition to digital narration, with best-selling books still being narrated by humans. Users may then complain about the quality of the digital narration, but will keep using such services as the price-expectation is now set.

--> A competition for better digital narration engines will likely drive evolution of the engine and authoring tools, further increasing the pressure of publishers to justify the bottom-line of per-book Audiobook production costs.

> Cherry-picking is easy, but I paid for this, it needs to be human quality throughout

That's a really interesting aspect. If the Audiobook delivers the content with a human voice but still not engaging enough, how many listeners would put the blame on the narration rather than the book itself... ("I like this new song of Metallica, but I don't like how they sing it")