I think Mark Hamill got into a car crash early in his career which scared his face up, so he went into voice acting. Plus if he stayed in video acting I'm sure it would have been rough since he would forever be Luke Skywalker. I bet even today he can't even pump gas without someone yelling out "Luke, I am your father!"
Those are bad pictures of Carrie Fisher. If she lost 20 lbs, with makeup and botox and good lighting she would make a fine older matronly Leia.
There is too much pessimism in this thread. New Star Wars movies will be made, and George Lucas will not direct them. Everyone should be happy.