The end game for North Korea is to climb down and stop threatening everyone; and indeed, China's new economic wealth, and her new middle class, with all the unproductive sabre rattling.
One sees a new regional resolve to no longer try to appease a tyrant!
When the north finally gets the message, that all the current approach is achieving is all negative, then maybe she will try a more conciliatory approach.
I see no prospect for a pragmatist like Obama, to risk his own skin in a futile attempt to go to north Korea personally.
His minders would counsel most urgently, to dismiss any such unthinkable thought stillborn. He could call the New Chinese leader and say, "Mr President, tear down this last vestige of the bamboo wall".
The real end game will come with reunification, and China could rise and rise in the opinion of most Americans; and the region, in promoting that very outcome, which is very much in her interest. Whereas, a regional arms race is definitely not!
Look at what happened to the once mighty soviet union, when she went down that very path!
Moreover, a China twisting the arm of the north and not only counselling reunification but subsidising it, would also signal other nations in the area, she is more than willing to negotiate effective peaceful outcomes, to absolutely any regional difficulty.
I believe this outcome would be hastened by the South and Japan announcing an intention to more than match the north, in nuclear capacity.
The north, with China's assistance or support has created this problem, which serves neither current common interest!
They need to be the ones that resolve it!
The north needs to pull her head well and truly in, given the current tension and the South's new resolve, to no longer submit to the north's completely counter productive tactics, has only one possible end point.
Rhrosty.

I really feel that Professor Hunter has fallen into the academic's trap of over-complicating what is a simple scenario (well perhaps that is how many academics make their living). North Korea has a massive million-strong army that receives the best of the state's meagre resources. It is in the interests of the generals who head that army to maintain this situation. Thus they have to manufacture crises at regular intervals in order to show the country they are needed. However, they would have no intention of carrying out their threats because, not being fools, they know this would be the very way to lose their prestige positions and probaby end up in the dock at the Hague.

Professor Hunter does make an interesting point when he recounts Kim Jong Un's message to Rodman. I have consistently maintained Kim himself might actually want more normal relations with North Korea's neighbours but has been hectored into being the front man for this crisis by the generals for the very reasons I have stated above.