If someone was going to be killed off, it would have to happen near the beginning of the movie. It then would have left the audience in more suspence after seeing a major character get killed early, they would be wondering what else might happen before the end. We all know that the rebels are going to win, but at what cost? If Lando died leaving the Death Star, I think it would have ruined the moment. The Emperor is gone, Darth is dead, the Death Star is blowing up!! Hurrayy! Oh shit, Lando just died. Not to mention the fastest ship just blew up too. What a killjoy.