Nuclear weapons have become the 'must have' accessory for any national leader wishing to avoid the blessings of western style democracy. That is surely the lesson taught by Libya and Syria.
NK has them, so the other countries around that state will have to adjust, as there is no affordable military solution.
Most plausible outcome is a South Korean nuclear weapons program, as well as a Japanese military spending surge.
Think those are both undesirable from a Chinese perspective, although the regime there may appreciate tensions as a distraction from domestic issues.
A more creative solution might be to help NK get richer. They would be less inclined to rock the boat if they had a comfortable ride.