..of old age in som expanded universe novel down the line.
With the success of the Clone Wars series this matter is highly irrelevant. I think many OT fans totally miss the point of this series when they stirring themselves blind on the continuity issues and how it fits in with the Previously made movies.
This is Star Wars right now and we don't know for how long really. And since Ahsoka is a major regular character she'll be along as long as we have the series. We know that she's not in ep III, but there's going to be a million ways of writing the series so that it fits with the rest of the timeline.
If she's going to die in one of the last couple of episodes to increase on Anakin's reasons to turn dark, they first have to be absolutely sure that they don't want to bring the series back in a couple of years.
By now it's pretty obvious how Lucas Film treats the storytelling of this series. It has a timeline, but it's more like they tell the tale of an era with unlimited numbers of adventures for our heroes. Yes, new characters can die, but Ahsoka seems to be specifically designed to bring in younger fans and girls, so to kill her off whenever would be a bad move from the business side of things. And I'd say that business trumps continuity in this case.
And I'm not just talking about selling toys here. As long as we have Obi One, Anakin and Ahsoka we can go on and on with this in between chapter of the Clone Wars. as soon as she dies we have to move on into the relationships of the movies.
Let's say that the animated series ends with Ahsoka alive, but in a position that fits with her not being in ep III. Then she can still turn up in a live action adventure set in the same time frame.
I'd say that she's not going to die mainly because the adventures of this era is told as multiple little stories not necessarily told in the right order, and that if the reason to have her is to add some cutesy fun in the mix it would be a too dark a turn to kill her.