The real skill of a voice actor is to collaborate with the writer on deciding the specific vocal choices to make during a performance to give it specific character and intentionality. There's been no work in this area and, indeed, it's hard to imagine how you would even design a system to annotate text with specific intonation cues that isn't many times slower than just saying the thing out loud.
eg: Imagine you had a WebMD page and you gave it to two different voice actors and you told one to try and make this drug sounds as promising as possible and another to make it sound as scary as possible. One piece of text can produce two vastly different audio products depending on intentionality. But with AI tools, there isn't even a setting for getting different audio from the same text and it's not even clear how you would build the setting that would allow you to convey what intentionality you want from the AI.
In short, there's a market for just handing a raw piece of text over to a human to convert into audio with no other interaction and that market is amenable to be taken over by AI but is already quite cheap and quite a small market. There's an entirely separate market where the voice actor sits down with the author and talks over what the intentions of the text are and how best to convert them to audio and nobody is thinking about building AIs that can understand intentionality any better than a human would.