Your view seems to be hyper focused on the most pessimistic way of interpreting things. Are you doing OK? Seriously, I know how easy it is for everything going on to overwhelm you with negativity. How are you doing?

I think it would be a good idea to do a section of your work with and without AI modification. Then have people listen to both and give feedback. Good to find out if people like the modifications before you do a tone of work.

That depends entirely on how profitable it is and how much they can get authors onboard.

I do agree that a good narrator delivers a performance that adds the work. James Marster will always be Harry Dresden in my head.