South Korea has a market economy that ranks 11th in the world to merge with starving North Korean like living in a big concentration camp? I don't think so. Yeah North Korea might have a nuke bomb but South Korea has equivalent to Israel's Iron Dome!
South Korea military has second best standing military in Asia next to Japan not counting chicom.
But the anti-communist old timers in South Korea are dying off. Young people there do not understand the evils of communism, and so are much less concerned about the North than their elders.
What exactly do you mean by “market economy”? All countries have those; it’s merely a question of whether that market is a free one or unfree one.
I would not say that a reunited Korea would be on the North’s terms, but it’s not out of the question of being on Red China’s terms. North Korea has been Red China’s sock puppet for decades after all.