Lucas has said flat-out that Boba Fett died in ROTJ and will never come back. So I don't see how which voice is canonical is actually being considered an impediment to how they can do follow up movies, the character is dead.
Firstly, I agree that revisiting Anakin's force-ghost would only serve to spoil "the tragedy of Darth Vader" arc of the first six films. Going further with that, I don't think they would/should approach many other force-ghosts of recognizable characters (except maybe Yoda), since what are they supposed to do? Bring in force-ghost Ewan McGregor for Obi-Wan? It is starting to sound like the segment of "How Return of the Jedi Should Have Ended", where Anakin's force-ghost morphed into young Ani (never have been sure how to spell his shortened name, surely not the very feminine Annie) and horrified the other force-ghosts by squeaking out "Now that's what I call Pod-racing!".
And yes, all official versions of the films should be available, for historical reasons if nothing else. Heck, it is fun to watch Lucas' decent into madness.
Oh, and darklordoftech, putting in parenthesis why you think SE changes matter doesn't mean they'll matter to me. So I'll say again, what about them?