If they could make Jeff Bridges younger for Tron Legacy, aging Ewan to Alec Guinness' age in Episode IV ought not to be a problem. It might even be possible to resurrect Alec the way Marlon Brando was brought back for Superman Returns.

Unless they bring Holochrons into the movies, I would think all Jedi records were destroyed or wiped in the purge. Unless Ben was making recordings on Tattooine for twenty years, he simply didn't have time to leave Luke any messages.

Otherwise, we're pretty much left with Force Ghosts. Ben suddenly appearing to Luke after all these years, to warn him of something dire would have impact though.

I have long thought Luke would go back to Ben's house in the Jundland Wastes someday.