[Crazy Jetty]

I dunno. There's *got* to be another clone wars type movie that happens just after Revenge of the Sith.
The surviving Jedi, including ahsoka would not just let Anakin get away with butchering everyone.
And Ahsoka is such a major character in Anakin and Kenobi's lives, I can't see her going down "offscreen" like most of the other jedi.
So either she dies at the end of the clone wars which helps trigger his decent into the darkside, or she dies shortly after RotS. Past that, she's one of Anakin's last links to his humanity, one of the last people left he loves like family. There's no way she'd live to Ep four, and not be a part of Luke or Leia's life. And I can't see her dropping into obscurity like Yoda or Obiwon. She'd have to confront and stop Vader. She'd feel it was her personal duty.
So, either she dies at the end of Clone Wars, or there's a post RotS movie where she confronts Vader and dies by his hands.