“Conquest” doesn’t necessarily have to be achieved militarily. There is some support for the Communist north already in the south. So, say a peaceful reunification happens and they hold elections.
If the whole north still votes for Kim, and 10-15% of the south also votes for Kim, won’t Kim be the ruler of all Korea still? Especially if half of the new country’s military divisions are still loyal to him personally?
That’ll never happen. The North Korean economy is 1/45th the size of the South’s. The people in the south are not stupid. There will not be a “one country” happening.
At best, and probably likely, there will be a cessation of the hostilities, and two separate entities trading vigorously.
There is zero chance that Kim becomes leader of all of a unified Korea or that there will be some national north and south election. Not happening.