With the rumors of Hamill and Fisher meeting with George a while back, I think it is likely that the treatments GL handed over to Disney take place some 20+ years after ROTJ and will involve the original characters/cast.

I expect to see Hamill, Fisher, and Ford return, although most likely they will be handing the torch to a new generation. They can easily get into shape and be made-up to appear for at least a few cameo scenes. Hamill would be the most likely to remain in the cast for all three films as a mentor figure.

If this is the case, I worry about the story. It will be difficult to continue the story that was so neatly wrapped up in ROTJ, especially if there is a 20+ year gap. If you're a fan of EU, you may disagree with me here, but I really don't want to see any cheesy storylines involving clones of the main characters etc...