So no answers, got it. I know you like "just asking questions", but I often times wonder if you really even think about the answers....
Oh and yes we'll know when an AI replaces an actor, especially the first time, as there is this little thing call the credits at the end of the movie. I know I watch them to see who is in the cast, and know many that do the same. So unless its credited as a specific actor, in which case they will be paid for the usage of their voice (is that really a cost savings), then it'll stand out as not being a real actor. And even if its a named actor I'm sure they'll let the world know it was AI that was used instead of them, and so it'll be know it wasn't a real actor nonetheless.
And I think you missed what I said earlier.... There are already Bills making there way through various state legislatures and even in Congress right now on limiting AIs usage. Some passing as recent as yesterday. There are even lawsuits and other legal things going on right now surrounding the usage of AI too, from copyrights to likeness rights. Once all this shakes out in the months and years ahead I'm fairly certain that we're not going to have this take over that you seem to envision is going to happen with AI in Hollywood.
Hollywood's legal eagles are on the vanguard of protecting clients about issues related to artificial intelligence.
variety.com
Along with a new bill just introduced in the US Congress, moves to put up new guardrails around AI are gaining traction
deadline.com