red_temple
Boo!
Okay, so he's not technically released from his vows. But if the wall does come down, and the Others overrun it, leaving most of the Watch either dead of in their wake, then Jon, as Lord Commander, will be in an unprecedented position to "redifne" the role of the Night's Watch. I'm sure he would stay as true as possible to their vows, but he also wouldn't just stay at the ruins of the wall and "guard" the kingdom from a threat that has already passed them by.