Wow. I could see this as threatening audio book narrators. However I would still prefer a real narrator to this in its current state. I think what it might be missing is different voices/accents for different characters.
I wrote a Perl/Tk GUI script for my file manager to manage text to speech through Festival 1.96 w/voice_nitech_us_awb_arctic_hts. Unlike neural network AI models it runs fine even on very slow machines.
Anyways the problem with this is it makes the product 'ai audiobook' basically worthless, why not just buy the eBook and have my personalized translator turn it into an audio book. Now you just have market differentiation between cheap ebook + ai narrator vs expensive + professional narration.
Though narration costs are already pretty cheap - it really does not factor into the cost of publishing an audio book that much unless its really a bottom of the barrel book.
At least they'll have to remain somewhat competitive once consumers decide they want the AI audiobooks and the like.