He is North of the Wall but with his green seeing he could follow/track the White Walkers as they move further south. It appears the White Walkers are not far from the Wall already so we might not even have a Nights Watch or a Wall for much longer to follow because 60 Crows and a wall will not stop the White Walkers and the undead.

Assuming Jon Snow is resurrected, I doubt he stays at the Wall and just reassumes his duties as Lord Commander.