If Luke actually turned to the Dark Side and became the Emperor's apprentice in Return of the Jedi, wouldn't he and the Emperor just die anyway when the Alliance destroyed the Death Star? If so, this takes ALL of the suspense out of the scene. If Luke turns to the Dark Side, the good guys win. If Luke doesn't turn to the Dark Side, the good guys still win.
Also, If Luke has faith in his friends that they will destroy the Death Star with him in it, why does it matter if he uses the Dark Side? If I knew I was going to die, I would just do what ever I wanted in the Throne Room.
"What? You want me to strike you down?! Don't mind if I do! All three of us are going to die, anyway! If there are no consequences for my actions, why not??"
The audience's worry that "Oh no! If Luke turns to the Dark Side, he will crush the Rebellion!" is ruined. Darth Luke can't crush the Rebellion if he dies aboard the Death Star!
This is kinda funny, but also worrisome. Is this a gigantic flaw? Or am I just a dumbo?
So my question is: what would be the dire consequences of Luke turning to the Dark Side, if any?