I always thought that since the acting was so poor in the final Hayden ghost image, that his smug, almost evil smile was the perfect setup for this being Vader's ultimate plan. To feign redemption to become the most powerful being in the Force. As Obi-Wan says, "If you strike me down, I shall become more powerful than you can possibly imagine". Vader realizes that Obi-Wan must have reached another level of which he had yet to achieve.

Thus, he contrives the plot, and at the end of 6, we see his success. 7,8 and 9 deal with Luke training and developing his Force skills to not only combat an apprentice Vader has taken on, but to also eventually achieve the power to destroy his Father once and for all.

Kinda kills the redemption aspect of the Star Wars films, but it was a nice thought.