In the future we may see likenesses of actors perform again after they're dead.

That's such an important distinction. It's true that an actor's appearance is one of their most memorable traits, but its not the sum of their accomplishments. Acting is a skill.

I'm not and never have been an actor, but I was impressed with Wil Wheaton, when he detailed on his blog how he prepared for auditions, the choices he would make about how to approach a particular scene. That level of thought, and experience will be lost forever when an actor dies.

With technology, we may see the likeness of a particular actor again, but we'll never again see their particular like.