I still say that the fact that everyone expects Ahsoka to die is the best reason for the show's creators not to kill her. Why settle for being predictable?
Because then we're left with the crap from the movies which seems which doesn't seem right for CW Anakin. I mean they could kill Obi-Wan instead if they don't want to be predictable but that might rub people the wrong way.
EDIT: Sorry about that last line, unnecessarily snippy. I just can't think of anything that would be more reasonable to push Anakin over the edge. He is obviously very protective of his padawan and I can't imagine anything that would be as affecting.