…I don't know how the Old Gods could possibly release him. So his only chance is if the other NW members say "his watch ended". Which they will, either if he is dead (and later resurrected) or they just think he is dead. Those words do matter (just like the words of the oath). If they say it, his watch clearly ended, even if afterwards he turns out to be alive. I think this is the way the NW can release someone (and probably Robb wanted to do something similar: he wanted the NW to declare Jon's watch has ended, and in turn he sends a 100 men.
As to whether he will stay there: I don't think so. By now he must have realised that the Watch alone won't stand against the Others. And Stannis made an excellent point: the North will more likely accept a son of Ned than him. I don't think Jon ever doubted that. He could bring the North together, especially now, with his wildling army, against the Boltons. He realizes how important that would be. But he never wanted to break his vows. But if he is legally released? I don't think he will stay as a NW member. But he will do anything to help them, like a Stark in Winterfell should do. He doesn't have to be a sworn brother to fight the Others.
Tricky question: Is Mance released from his vows now? When "he" got burnt, Jon said the words. Is is valid now? Because from now on, it would mean he is not a deserter, he got released legally.
More to the point, do you think every man in the Nights Watch is going to agree on whether Jon is free of his oaths? It's not a question that has ever had to be asked before and the response from the new LC (if one is elected) is likely to be politically motivated. If Marsh or Thorne is in charge they would be less likely to allow Jon to go his own way than to order him to be killed again. If Jon loyalists are running things they might tell him how everything has gone to shit since he died and he needs to sort it out.
My main reasoning though is that I believe Robb was very smart and able to kill two birds with one stone. The Karstarks were in rebellion but Robb did not hate them and needed their swords so he must have wanted to win them back not destroy them. Harrion was with Glover's army (probably in custody or on parole) and Robb was expecting to meet up with them before arriving at the Twins. Harrion (Robb presumes) hates Robb so Robb would have to keep him prisoner to keep the rest of the Karstarks in line. But if Robb died in battle then Harrion is on hand to take over and would no longer have any Starks to hate, and the loss of the northmens talisman is mitigated by the fact that all the houses of the North are united again.
Edited by Buried Treasure, 18 March 2012 - 06:06 PM.