The 'Lighter' Side Of The Force
I was hoping Lucas would reveal in Ep. III that Obi-Wan was in fact, Luke and Leia's father. Padmé and Obi-Wan's affair (once Anakin learned of it) would have been the ultimate catalyst to push him to the dark side, and made the final lightsabre duel even more emotional. I suppose this could still be a possible twist for EP. XIII, although I'm not sure how Rey and Snoke would factor into the story.
(PS - Padmé would have had to take this secret to the grave with her.)