Sansa isn't going anywhere. I'll refer to a previous post of mine:
http://www.sffchronicles.co.uk/forum/47935-next-shocking-death-2.html#post1200455
In there I base Sansa making it through simply on the fact that if she dies no one would really care. Killing Starks is an art form for GRRM. When he does it he wants it make a huge impact on the reader. Unless she undergoes some pretty severe personality changes, no one is going to be floored by her death in the same way they were floored by Ned's or Robb's or even Lady's deaths.
The post after mine, by Gambit, also brings up a great point. If Sansa dies then we lose the only POV in that area of the world and miss all of the rest of Littlefinger's machinations. GRRM wants us to see that stuff. You can tell he really likes writing about Littlefinger.
Edit: Just noticed the post after Gambit's, by TK-421, also brings up the Littlefinger POV point.