You can't replace the original actors with new ones because it's just not right. And few, if any, of the originals (who showed their faces) will return for more. Fisher won't do it. Hamill doesn't show his face in front of the camera unless covered by a mask or makeup due to his skin graft scars showing. Ford likely won't although his recent career moves prove that he needs any boost he can get. Guinness is dead. Williams might return.