Well, an intent of Apple seems to be to break the price of an Audiobook into license and production cost, take control of the production using AI and pay only the publishing license, instead of having to buy the rights to sell an Audiobook as a separate work of Art (because in the end, their engine will create the work of Art from the written word).

Sadly I don't see how this will make Audiobooks any better than human narration could. It's more about streaming platforms taking more control over the content and have experienced people train their proprietary TTS engine along the way.

Just to avoid confusion on Librivox: They offer Audiobooks of works which are already in the public domain (so not only the Audiobook is in public domain, also the rights for the book have already expired). So it's a platform allowing people to make free narration of already-free content.