Correct me if I'm wrong, but didn't Lucasfilm restore the entire original film before doing the special edition CGI inserts? So they might have scanned the bits and pieces of the recomposited original effects stored somewhere, splice them into a video timeline and use that for an oot release?
Not ideal, but it's better than nothing.
On another note, can't wait for the Ep 2-3 4k 16 bit scans! Oh wait...