Neither US or NKorea want war. NK needs aid from US and South Korea (food supplies), US needs tension in region to sell their weapon systems (i.e. F35, naval systems,...). Nobody wants to start a conflict and eliminate NK goverment, because they will have to create new or worse, unite both Koreas.. Look at East and West Germany... more than 20 years since Berlin wall falls, and there are still great economy differencies. Imagine North Korea as an agriculture, military based economy poor country that would need to reform and invest HUGE amount of money for DECADES to raise their health, educational, .... system to kind of eastern european country level.
In military, NK is dangerous. Not because their rockets and nuclear weapons (they still dont have adequate nuclear warhead), but because of their numerous artilelry aimed on SK, especially on Soul. SK and US would need a days or weeks to eliminate all artilery threat, but until they will do that, there would be thousands of South Korean victims. You cannot simply bomb all arty sites at one time. Of course, you can try to destroy communication, eliminate military command, but not in few hours..
One positive of another Korean war could be another MASH series.
