So at what point do the actor's/actress' talents become obsolete?
Actors are still artists - a good actor can bring a lot to a performance even if they're just voice acting or mo-capped. Golum had a live actor bringing him to life, as did Sonny in I, Robot. The CGI folks drew heavily on the actor's portrayals. A lot of directors see their relationship with their actors as a collaboration and some tend to choose the same folks over and over because they work well together. From what I've seen in the special features sections of some animated movies, the voice actors are filmed while they're reading and some of that performance gets incorporated into the film. So I think there will be less room for mediocre actors, and the "extra" may become obsolete, but I think there will always be room for the person with a talent for acting or performance.
The bright side that I can see is that perhaps not having to put up with so many dumb, uneducated actors as public role models and political activists.
Well professors should lecture and artists should speak through their art. It's really annoying to get lectured when you're expecting art. People should stand for what they believe in because it's the right thing to do, not because all of the cool kids are doing it or because it helps their image.