Its weird territory here. Ultimately the idea of force ghosts gets a little weird if you think to much about it. The only appear for Luke's benefit anyway. You start thinking about Obi-Wan and Yoda and Anakin all sitting around playing cards as ghosts and it gets pretty hokey. Anyway, Its hard for me to imagine we are going to get a lot of Luke in the movies, so I don't think we'll need to get any Vader.

Im sure they're will be some, but I bet we get Yoda and some other Jedi ghost that hasn't been seen before. And possibly Liam Neeson or Ewan McGregor.

McGregor tweeted this morning "Wonder if theyre gonna need some Jedi Hologram action."