Extremely worrying for South Korea and Japan. Not sure how China treats this. This is like a crazy neighbor who you learn just got a gun.
South Korea is used to it, in fact war never officially ended between NK and SK.
North Korea always had guns and South Koreans are prepared for the worst. The only way the NK regime could survive(international aid) is looking crazy, but not too much. Too much and they will be wiped from the face of earth. Too little and they won't get aid, and people will revolt against people in power.
Also, I'm glad you brought up the point about a neighbor with the gun. When somebody has a gun, you're not likely to walk over and screw with them. Nuclear weapons have lead to a great peace between nation-states.
But, I think its an open (and rather scary) question as to whether MAD will continue to work with multiple parties some of whom are batshit crazy and have demonstrated utter disregard for the safety and well-being of their populace.
Is their leadership insane enough to sit in a well-stocked bunker while setting off an H-Bomb in South Korea or elsewhere.... umm yeah, I think so.
Let's not forget about the millions North Koreans who would die as a result. They're people, and the number of them who are culpable for their regime's madness is a rounding error.
I've always felt that the best strategy against NK is to simply wait for the regime to collapse on its own (along with sanctions that isolate them, FWIW). This is fine as long as they don't try to invade South Korea, leading to swift US-backed retaliation. But perhaps now as they continue to develop and "show off" their nukes, they'll feel emboldened to "try something" before their time runs out?
It's Brick in the first Anchorman fight.
Getting to play in the south China sea at the expense of instability in east Asia is probably not the bargain they are after.
NK is to China what the sidekick is to the strongman. or the Capo to the Godfather. He's insufferable and creates you headaches, and provides diversion, but he's your sidekick... except if you go to far one day, it'll be goodbye.
I don't know much about geopolitics so I could be very wrong.
The groups that would take control:
Japan: Likely already have this tech, ally of US
Korea: Likely already have this tech, ally of US
Russia: Already have this tech
China: Already have this tech
USA: Already have this tech
Or do you mean some minor group, rather than a state taking control of a failed NK?
People.
Imagine if you were given this scenario: "x" people will be killed tomorrow, you can't change that. There are three options for which people will be killed, either "well-off", "in poverty" or "random". You can choose one of the three, if you don't make a choice then one of the three will be randomly picked and the deaths still occur.
Would killing the people in poverty be better because you're wiping out more misery, would it be worse because you're letting financial state influence death?
And as much as ethically we want to think that all people are equal, let's not forget that most armys would be willing to kill 10 opponents to save the life of 1 colleague, and taking the US as an example I suspect (could be wrong..) a poll of the US would see most people willing to kill 10 North Koreans to save the life of 1 American, without having any other information about the 11 people who might die.
It depends WHY it falls. The existing system is almost completely military with a sorta civilian mostly hereditary aristocracy leading it. So if it falls because the military collapses it'll be nearly a wasteland, total anarchy, but if the military stays in total power then instead of hereditary civilian aristocracy they'll have a genuine combat soldier (or at least a semi-experienced general) in charge.
At the very tippy top the Chinese like their buffer states, and are not going to be happy with reunification with SK. Of course the same people said the same things about Eastern Germany.
The problem China does not want to have is a US ally at his border.
In the last decade or two, I doubt China wants a more dangerous North Korea. It could be that NK is attempting to play China like it plays the rest of the world. We always assume China is pulling all the strings but maybe NK knows some strings it can pull too