AI-generated content is not eligible for copyright.
That’s just not true, no matter how often clueless artists repeat that. What’s not copyrightable is completely AI generated simple stuff, like type “car” into StableDiffusion and copyright that image of a car. That’s not eligible for copyright and rightfully so, since that would turn AI generation into a minefield if people could copyright sections of it in bulk. But nobody does that anyway.
People want full books and games and stuff, not singular images of a car. For the time being at least, any full game or book will still be full of human input, it’s not something the AI will spit out without effort. You still need numerous different AI systems, custom training and a whole lot of manual back and forth before you get something to your liking. And the result of all that effort will still be copyrightable.
There might come a day in the not so distance future when AI can do it all by itself and make the whole game or movie from start to finish with no human input. But at that point you aren’t just replacing the actor, you are making Disney obsolete, as you no longer need static content, you can just generate it dynamic on the fly like you are on the Star Trek Holodeck. But at that point the fate of the voice actor will be the least of your problems, as you just made a whole lot of other human jobs obsolete too.