"I'd be up for it. If they need me to be Obi Wan Kenobi, I'd be happy to do it. Who knows what the story would be? How could I be Obi Wan Kenobi? Oh, I'm in the Force? With Liam [Neeson]. We're in there together? I'm up for it anyway. I will don the cloak again."
Of course, if we're going to see any Force Ghosts in Star Wars: Episode VII, Hayden Christensen's Anakin Skywalker would seem to be the natural choice (given his insertion into Return of the Jedi, and what have you), but with the studio said to be looking at standalone movies after Episodes VII, VIII and IX, perhaps there's a chance of a solo Obi Wan movie somewhere down the line. After all, there's plenty of time for an adventure or two between Revenge of the Sith and A New Hope.