It seems pretty clear that what's driving the current escalation of tension is North Korean politics, and IMO that is probably what will settle the crisis one way or another. No-one is likely to to launch a pre-emptive strike against NK, but if it does carry out its threats to attack South Korea, Japan or even the USA (although that's probably an empty threat) then there almost certainly will be a military response, whose scale will be determined primarily by how far the Americans think they can go without pissing the Chinese off too much.
Kim Jong Un is inexperienced, and in a weaker position than his father. Historically, NK has tended to use threats to win concessions or greater aid. If Kim can deliver that this time then his game of bluff will have worked and that will strengthen his domestic position. Problem is, it's clear that the Americans and others aren't going to play that game this time. So if Kim can't deliver, what then? Being seen to back down could damage him fatally, and it's not inconceivable that hardliners within the military could push him into a situation of having to start a war or face a coup, which is where the real danger lies. Either that, or a different and perhaps more moderate element within the regime could topple him. In the end, we don't really know enough about the workings of the regime and the factions within it - insofar as they exist - to judge.
It's all a bit redolent of the Cuban missile crisis, in a way, although a lot less scary as the chances of it spiralling into a major nuclear war are slim. Either way, it's all very unpredictable and could end quite quickly and potentially very nastily indeed for the Koreans on both sides of the border.