To me this has one clear ending. Sansa somehow kills Littlefinger. There was the prophesy, I forget which book which indicated that Sansa will kill the "giant man" which is littlefinger. A nice play on words. The character to watch here is actually Robin. Robin loves Sansa, and Robin has all the power, he is the lord of the vale. If Robin feels that Littlefinger is going to take Sansa away from him, there are any number of lords of the Vale who would love to help Robin with his problem and gain the support of the future lord. We assume Robin is weak because he's been written that way, but why? To subvert expectations.
At some point the Vale will be word of what happened to the lord commander of the nights watch. Sansa will bide her time.
When Sansa then later hears that Jon is in fact not dead but marching on Winterfell, she will see her chance to go home. She will trust Jon more than anyone else there. Only Robin can make that happen. So she slips the truth to Robin of who she is and has Littlefinger removed so that the Vale can send a contingent of men to help retake winter fell.
Not sure how they would get there though with the roads and everything.
Its easy to under estimate Robin, but important to remember, he is the one with the power, not little finger. Robin is in many ways similar to Joffrey.
My guess is that Sansa winds up with either Robin (as his mother wanted) or she never in fact separates from Tyrian and perhaps Tyrian winds up rescuing her from little finger somehow.
