At present, there are an estimated 25 million North Koreans. It’s remarkable enough that the population is supposedly growing with the scarce food resources. The horrors one would find would likely include cannibalism, as what else would one be reduced to when the alternatives are eating grass or stripping bark from trees. We’ll never get explicit truth from the media, because they don’t want the world to know the horrors of leftist regimes and the mass casualties they incur.
Imagine such people becoming an instant and permanent underclass in a newly reunited Korea, mentally ill-equipped to deal with new realities of this age (whereas before their sole duty was #1, paying absolute deference to their God-Dictator Kims 1, 2 & 3 and told what to think, how to dress, how to wear their hair, et al; and #2, trying to find a bare minimum of food to get through the day. Education ? Whatever horror indoctrination presents their God-Dictator as the provider of everything and anything and being grateful that he allows the sun to rise and to set. The kind of propaganda we saw from our own media during Zero’s 2008 campaign, epic-level Satanic sicko stuff, “Second Coming”, et al).
Assimilating people of Stone Age mental capacity into the modern era, ones whom have worshipped a deranged Eric Cartman-esque cartoon character as absolute God, with little to no critical thinking skills or other positive attributes are likely a future drain on a United Korea and perpetual welfare cases as well (and also probably a powder-keg for future violence/crime when they cannot cope with being thrust into the modern era, let alone able to compete with their Southern cousins, and acting out as a result).
China knows this has all been going on, but are probably content to keep NK as a bulwark against a free South Korea. They could’ve marched into the NK decades ago and taken it over, but were content to keep it as an ally, as they weren’t much different than China (pre-Nixon’s visit). It’s more of a headache for them today, and they’d not want to deal with the logistics of a takeover and the nightmare of what to do with the impoverished and subjugated population.
China may think they are engaged in cold realpolitik. On the other hand, they are not good at making decisive changes. They could be brutal but their leadership runs on inertia. They are kicking the can down the road, exacerbating the problem.
There is some consensus in S. Korea which is that the border(DMZ) should be maintained even after N. Korea has become part of S. Korea. N. Korean defectors(refugees) themselves acknowledge that it is really hard to adjust to S. Korean society. They speak the same language and share same heritage, but in reality, S. Korea is as alien as America. Two groups are culturally segregated. So it may be good for both groups to stay inside their region for a while. S. Korea may have to relocate all their outsourced factories to N. Korea. They could provide cheapest labor in the world. It will keep them productive and raise their living standard. It is better that way than coming to S. Korea and finding themselves completely useless.
What the South Koreans should do, is send 5000 missionaries into the country after reunification, and share the gospel with Christ.
What bulwark? China and South Korea are practically best friends now - and they share a deep hatred and distrust of Japan. China's only interest in propping up the North Korean regime is in keeping millions of refugees from flooding north across their border. They have simply made the cold calculation that it is better for millions to suffer under the Kim tyranny than to have to deal with the mess after its fall.