Back to the OP; certainly interesting to think how the story could have evolved with Vader, Anakin, and Kenobi being 3 completely separate characters, but also good friends.
Is there any fan fiction continuing on the premise in Leigh Brackett’s 1978 draft of Empire Strikes Back? Or similar media such as an “animated comic” type story?
I have not found any. I hope someone else knows of some as it is such an interesting idea.
There are some good fan stories and analysis of early drafts here: www.starwarz.com/starkiller/category/fan-creations
It does make me wonder how George would have wrote Vader and Anakin being the two separate characters in the films, and if and how he’d have used that ‘Vader, still pretending to be a Jedi, repeatedly lured the few remaining Jedi left, to their deaths’ idea.