According to defectors connected to the NK government:
In the 1990’s, the North determined that they could no longer defeat South Korea in a war. They simply don’t have the military infrastructure to pull it off. They can’t even perform large-scale exercises anymore. They also cannot trust their soldiers to get past the first grocery store.
If it happens it won’t be by military conquest. It’ll be a reverse of what happened in Germany. The younger generation there appears to be that clueless.
China eventually wants to make nice with South Korea and become partners in the new “Greater East Asian Co-Prosperity Sphere”. Both China and South Korea wish the North would go away...but both know the flood of refugees from the North would pour over both borders and create a huge burden on both countries....so ultimately both will have to work together to solve the “North Korea Problem”, once the Pyongyang Regime collapses, which is inevitable.