Apple Martini, on 07 November 2011 - 06:33 AM, said:
To kind of wrap everything up in one package, I'll just say that the series isn't over yet and it's possible that the Night's Watch might surprise you. Kind of a pat answer, I know, but I don't think it's fair to make a judgment call when the most critical part of the story is still to come. There's no way to predict what the implications will be after the, uh, incident in ADWD, and depending on the aftermath of that, the Night's Watch might look very different.
I was kind of afraid you might say that.

So what you basically need for your theory to work is the fundamental change of the NW. Imho nothing in the text so far suggests that this kind of change is to be expected. I mean, they murdered Jon to prevent this kind of change. And Jon... wanted to strengthen the NW, yes, but he mostly tried to include other forces.
There is however something in the text that would support the likely failure of the NW, quoted upthread by Kissdbyfire:
Kissdbyfire, on 07 November 2011 - 10:30 AM, said:
“Bran found himself remembering the tales Old Nan had told him when he was a babe. Beyond the Wall the monsters live, the giants and the ghouls, the stalking shadows and the dead that walk, she would say, tucking him in beneath his scratchy woollen blanket, but they cannot pass so long as the Wall stands strong and the men of the Night’s Watch are true.”
Since stabbing your LC(s) probably doesn’t qualify as ‘being true’, could this have an impact on how the Others become able to come south of the Wall?
That quote seems to foreshadow the eventual failure of the NW imho. Of course your more optimistic read of the situation post assassination attempt might win out, but for a full-out war to start, we would need the Others to be able to cross the Wall somehow.
Otherwise this war would still be locally confined. In the South there would still be petty dynastic squabbles going on while in the North the NW heroically defeats the antihuman forces of the Others, thus fulfilling their destiny. After the war, since the NW wins no glory and so on, nobody in the South will much care about what had been going on there and there will in fact laugh about the ridiculous old wives' tales they hear from the North - grumpkins and snarls indeed.
But really, the situation at the moment is this: The NW don't know anymore about the threat of the Others then most everybody else in the seven kingdoms. The Wildlings likely know more about fighting the Others then the NW. And they're not interested in learning more either with the exception of their (former) LC Jon Snow who they just murdered. Where do you see the sparks to light the fire? I'd sooner think they're about to be wiped out.
Apple Martini, on 07 November 2011 - 06:33 AM, said:
It's also possible that Lightbringer is symbolic in a normative sense, and that the Night's Watch must remember its purpose before it can truly become Lightbringer. In that case, it'd be about the Watch fulfilling its potential. Being Lightbringer isn't just about what something is, it's also about what it does.
Hmm, that sounds very fine and good, but I really don't see how that could possibly happen. We have to work with the men we have, there won't be any others. And Jon repeatedly remarks how all the good men of the NW are gone and he cannot rely on any of them. I totally agree with him there. From what we've seen (ok, via his POV, but I still think it's rather reliable), they're a bunch of narrow-minded idiots who just want to keep everything the way it always has been which is of course a very human desire, but won't be of much use when facing a new threat.
So there is a very real danger that "Lightbringer" in this normative sense might never reach its full potential.
On a somewhat different note: if you think it possible that a body of men could be Lightbringer, how about a single man who swore the oath and is still true, say Samwell Tarly? I really don't see much difference for symbolic value there. And I guess it will make a difference whether the NW men swore their oath in front of a heart tree or in a sept, because of the Old Gods magic in the Wall. We'we already seen that at work when Sam crossed the Wall throught that Gate and I expect it to come into play again.