Since we're so close to the Battle of Winterfell and the Internet is rife with speculation, I'm going to do the opposite and post 5 fantastically impossible outcomes:
1. Dany awakens the Doom of Valyria, the King of Dragons from the Targaryen sigil; King Ghidorah..
2. John Snow nee Targaryen discovers he is the reborn Azor Ahai. He shouts the secret magic words to end the Night King once and for all.
Yol-Toor-Shul
3. The army of the living loses and Sansa is forced to tap into the Phoenix force to turn the tide.
4. The Night King beats the army of the living before moving on to the rest of world.
Satisfied with his victory over the heroes, he then retires to a life of vegetable farming.
5. Bran manages to commune with the souls of the dead Starks under the crypts and bargain with them to help the living.
An army of green spectres emerge from the crypts and the barrow lands to defeat the undead.