I've wondered at what point this would happen. I think it could now, but from what I've read the voice actor unions are able to prevent it currently (at least for AAA games or non-indie devs). Many of them have agreements/contracts in place for the foreseeable future, and being the first big company to replace them is a heap of terrible press that nobody is going to want to touch. I think it's the same reason Hollywood reached the AI agreement recently too.
