Well....technically that wouldn't be much of a stretch since he'd be one with the force and all that jazz. I don't think that anyone, is even remotely thinking that they're be back flesh and bone. To have some of the greatest JEDIs that all played a role in what was probably the galaxy's greatest battle, make sense as long as they stay ghosts mentoring or guiding someone/something.

They're doing what Lucas did with Attack Of The Clones at this point. Using nostalgia as a means to "make a good movie", which never ever works since it's just basically pandering. Stop shoehorning every goddamn character from the original trilogy. And how they still whore out Darth Vader is still pathetic (he's set to make an appearence on ESPN on some random day for no goddamn reason whatsoever).

Screw Disney.

Vaider does appear as a force ghost to one of his descendants to ward him away from the darkside. Star Wars has a lot of masters reappearing as force ghosts in the comics.