There's a difference between taking one thing and putting something else in it's spot, and truly REPLACING something. Yes, some ads have AI generated actors. You know because you can tell because they're "not quite right", rather than focusing on the message of the ad. Noticing AI in ads turns more people off than on, so AI ads are treated by a lot of people as an easy "avoid this company" signal. So those AI ads are in lieu of real actors, but not actually replacing them because people don't want to watch AI actors in an ad. The ad ceases to be effective. The "replacement" failed.
Realistic video generation only became a thing in the last year or so.
How long do you suppose it will be before we can't tell the difference between it and reality anymore? A few years at the most. Then what?
I don't think AI will ever be able to compete with real actors, not in a meaningful way.
Animated films have competed for box office dollars since basically the dawn of cinema. Animated characters have fan followings.
Just wait; the stuff is coming. Ultra-realistic full-length feature films with compelling AI characters that are not consistent from beginning to end, but appear in multiple features.
The public will swallow it up.
Animation is drawn by humans, not AI. That's why it sells, it still has heart and emotion in it.