I think a very good idea for a plot for a stand alone movie would be: A very old Ahsoka Tano approached Luke Skywalker with a Holocron from the Jedi Temple. During the exchance Ahsoka tells him that he once was the Padawan of his father during the Clone Wars which obviously hightens Luke's Interest more. " You knew my Father?" ask Luke. " Yes! He was my master! And the only one who sttod by me in my hour of need. " Answers Ahsoka which cues a flash back to the Clone Wars when the she decides to leave the Jedi Order. What Happens next? Well just about anything? She could join Ventress in attempting to defeat Dooku! She travels back to Mandalore and hooks up with Lux Bonteri where they temporary join the Death Watch. She begins acting on her own accord like a Vigilante tracking evil characters like Cad Bane and Aurra Sing which eventually leads her too Lord Sidious.