SilverWook said:

I used to think perhaps Anakin would live a double life as Vader for a time. (Perhaps undermining the Jedi from within?) The sith(?) armor and voice being his disguise. After the lava planet duel, it becomes his full identity, as Palpatine would need Vader's established reputation to get things done.

I think something like this would be awesome. I think I had a similar, though not quite so extensive idea in the radical redux thread. But it seems like references could be made to a rumored assassin called Darth Vader in Episode III. Ideally Kenobi would also have another apprentice who turned to the Dark Side as well. All references to Anakin as Vader would be removed (and perhaps additional material introduced where Palpatine orders the mysterious Vader to hunt down the Jedi). In the end we imply that Anakin dies of course, and the mystery is preserved.