Way too deep for Lucas. He's not nearly that talented a writer.  A really interesting idea, by the way.

Is there actual evidence that that really was the "original vision"?

I’ve never heard some of this information before.  Does anyone know the author’s source?

^From a certain point of view perhaps (as in it's previously reported but unsubstantiated gossip).

This isn't the original concept.  That comprised of a screenplay over 300 pages long (which is currently being adapted for The Star Wars comics).  Instead, what we have here is a number of various ideas from various stages of development.

I don't think there were any "original plans". Lucas just came up with the storyline for each individual film. I mean there are some rumours that Lucas had some long term "plans" (like from Kurtz who I lately don't find a reliable source at all) but I think that is all bullshit.

I see no evidence to doubt Kurtz.

I imagine Lucas made and adjusted plans as he went along like most writers do.

Kurtz was likely to be exposed to some of those earlier plans some of which made sense (like Leia not being Luke's sister) others did not (like Ben and Yoda physically returning from the dead to aid Luke in his final battle against the Emperor).