Yeah, that was a little strong. What parts of the setting did you want to engage? I guess I just find a straight removal like that to be less interesting. My idea of a fun "what if" would be something like Luke turning to the Dark Side in RotJ, or Vader's plan to capture Luke working in Empire, or Vader failing to kill Palpatine. Maybe the Death Star succeeds in destroying the Yavin base, and the Rebellion comes under new leadership, but with most of the mains intact and doing other things. Maybe Luke stays on Dagobah with Yoda and finishes his Jedi training, and Vader resumes his hunt for Luke.
Heck, maybe Vader defeats Obi-Wan on Mustafar and never gets cyborged. Just removing the mains without changing anything else seems almost gamist to me, a rationalization to have the PCs take their place. Of course, there are fun possibilities with that too. It's just not what I would do.