The 'Lighter' Side Of The Force
If Obi Wan had been killed, there never would have been a Star Wars. Episode IV begins with Leia programming Artoo to ask Obi Wan for help. "Help me Obi Wan Kenobi, your my ONLY hope", and if he was their ONLY hope, then if Obi Wan is dead, there is no hope to save the galaxy. The Emperor, Darth Maul and Darth Vader would be alive and running the galaxy in the most corrupt manner, though the saying "Two's company three's a crowd" comes to mind, as I think one of those three would be murdered by the other two.