I doubt the second korean war will ever begin. The only way I could see war once again is if it involves WW3. It would just be apart of a greater battle, not it's own thing.
But anyways, I fail to see N. Korea's power other than nuclear weapons.... all their equipment is terribly old, they don't seem to be modernizeing it, either. Their soldiers, while dedicated, I don't believe they have the uh....... physical finesse now seen in today's armies. Now, I think the north has a extremely good chance of keeping N. Korea together in a defensive battle, that entire nation is so nationalistic you'd have to kill everyone to take it- but going offensive in the south? No, they might be able to push in a ways, and obliterate the capital. But no more, they could never reunite korea by military force and under the red star.