The recently-released coffee table book Art of Star Wars: The Force Awakens has concept artist Ian McCaig discussing initial plans to have Hayden Christensen return as a sort of half-Jedi, half-Sith ghost in Michael Arndt's famously-discarded version of the script. Take a look at the art above and below; In that version, Luke would have appeared a lot earlier and been involved in more of the story, with the fluctuating ghost of Anakin Skywalker/Darth Vader occasionally peering over his shoulder, like some sort of Force-sensitive Jiminy Cricket. McCaig had this to say:
"When you light a candle, you also cast a shadow. That inspired me to propose, for the first time, that Anakins ghost could come back... If we see Anakin Skywalker, because he does flow back and forth between Darth Vader and Anakin, lets see him as a character with a dark and light side. The reason Luke is this whole new entity is because he was the first to acknowledge his own dark side that it was not separate from him."What "whole new entity" McCaig is referring to remains a mystery, but it's clearly some holdover from the old version of the script (and rather unlikely to remain a facet of Luke's character when Episode VIII rolls around). Although visually it's an extremely cool idea, I don't think anyone was in a hurry to see Hayden Christensen's acting career make a comeback. A limited involvement may have been acceptable, as McCaig makes a good point there about the duality of the Light and Dark Sides of the Force, and the idea for it was sound. In any event, it matters little to The Force Awakens, as JJ Abrams and Laurence Kasdan went back to the drawing board and cut all of the Luke-centric stuff out. Not to scare you all, but it doesn't necessarily mean we won't see Christensen make some sort of cameo appearance in the next two instalments. Star Wars: The Force Awakens is out now.