why I think Sansa will die
I think it'd be too much to hope for that the remaining Starks will all make it out alive, especially if you take into account the undead army making the wolf sigil shape in 7x07.
Beyond that, further clues I think pointing to it being Sansa.
*minor potential spoiler the rest of this little paragraph* In GRRM's original outline, three of the main survivors are Jon, Arya, and Bran, no mention of Sansa.
Beyond that. Sansa has fought the hardest to reclaim the name and identify as a Stark. When they first meet Lyanna Mormont, she talks about how whether Sansa is a Lannister or a Bolton, and Sansa defends that she has always been and will always be a Stark. In the Season 6 finale, when she and Jon discuss who will sleep where, "I'm not a Stark." "You are to me." She is Lady of Winterfell. Of the four, she places most stock and weight in the names and titles of their heritage.
The other three all have other identities to embrace. Jon is literally a Targaryen, not a Stark. Arya has learned to become No One, and anyone. Bran is the Three-Eyed Raven.
I think all these point to Sansa dying. Thoughts?