What’s his arc now besides possibly being the King? This whole series has been him leading to this battle against the dead, and now it’s over. Him and Cersei/Mountain have no deep connection, like Jaime/Tyrion/Sansa/Arya or even Dany. What’s left of Jon these next three episodes? He’s the biggest character on the show and I have no idea what the big climatic Jon story will be
All sorts of ways they can still go with it....
1) Cersei / Golden Company kill Dany, Jon takes vengeance and the throne.
2) Jon dies in the battles with Golden Company / Team Cersei. Dany takes vengeance and the throne
3) Jon / Dany both survive to the end, overthrowing Cersei. Dany takes the throne, Jon becomes Warden of North, King of the North, etc. This requires Jon to bury the secret of his rightful claim to the throne.
4) Same as scenario 3 above, but Dany and Jon rule together.
5) Dany, in a jealous rage of Jon’s rightful claim to the throne, begins to become mad like her Daddy. She kills Jon to prevent his taking of the throne.
6) Same as scenario 5 above, but Jon fends off / kills Mad Queen.
The key point is that the whole series has not led up to the battle with the NK. It was trending that way before the middle of Season 7, but the budding romance with Dany and his true bloodline being revealed made his scope much larger than the champion to defeat the dead.