Simple fact: China is the key. If China wants the norks to fold, they will; if not, they wont. To avoid war, pressure must be applied to China.
Getting more and more information about the outside world into the general populace of North Korea could also serve to undermine the regime. There are already some signs of it as technology despite all of the controls by the regime is allowing it to creep in and the populace is becoming increasingly aware of how much worse of they have it than other nations.