I'd clearly made the mistake of thinking that Jon and Dany, plus maybe Tyrion, are the only "untouchables" in this series (at least for this book).
A lot of comments seem to think Jon's actions were blatantly leading to his demise, but let's face it, we could say that about ANY of the characters. Granted, as soon as Jon declared taking Winterfell I should've thought of Robb and known better! It took me by surprise though, and had me doing a double-take, just like the Red Wedding, even though not on the same scale. After I re-read words to the effect of "he twisted away from the blade" I thought, "no no, he's all right. Heh, that tricksy Mr. Martin is just giving us a scare." Then I read the next few sentences...
For those arguing that Jon may not be dead, I think that's seriously wishing thinking. Stabbed multiple times and I get the impression that his throat was cut far worse than he realised, hence his fingers not quite able to grasp Longclaw. Jon is surely dead. A red resurrection seems just as sure (except that warging offers an alternative).
My only question is why wait until all the wildlings were through the Wall before turning on Jon? While the Hardhome mission was far from helping, letting the wildlings through must've been the issue that turned popular opinion against him.