The problem of North Korea is hugely overblown. It is also easy to solve.
First, forget about forcing Kim to abandon nukes. Not gona happen.
Second, remove all sanctions from NK. Engage it into international trade and cooperation as deeply as we could. This will create effect similar to the one in China. That is new class of well off even wealthy people will arise. Kim will not be able to stop this force of nature. They will demand (softly but strongly) to have a say....
I think you've fundamentally misunderstood the nature of the North Korean state system.
It's a very old-fashioned system. There is a divine ruler, someone who is officially regarded as above human beings. The official press tells North Koreans that wild animals & birds acknowledge the rule of the Kims, that the weather recognises major events in their lives by cessation of storms & the like, & that they have other superhuman characteristics, such as being able to excel at anything they choose to. For example, tt was officially stated that the one & only time Kim Jong Il played golf (to inaugurate the first golf course in N. Korea, IIRC) he was officially stated to have made 18 holes in 34 shots, including five holes in one. Achievements in rocketry, nuclear explosives, etc. are due to the Kims telling the scientists & engineers how to solve their technical problems, after a mere glance at the hardware.
It is inconceivable that someone at the head of such a system would agree to give people outside the leadership a say. That would destroy the myth. Fat boy would, & probably rightly, fear that abandoning his status as God-King would swiftly be followed by a humiliating as well as painful death at the hands of the disillusioned populace.
Don't forget that this is a man who does not hesitate to kill his own family if they're insufficiently servile. He had his uncle executed, reportedly by anti-aircraft gun (& is reported to have gleefully watched), & his brother poisoned in Malaysia.
The leadership in China chose to open up. The Kim kingdom has not made that choice. It does not want openness. It wants control above all else. The poverty of the people is of no importance to the Kim dynasty. It's a bit like Orwell's vision in
1984: a small privileged group, an outer semi-privileged group (one of the privileges of which, for example, is living in Pyongyang), & semi-slave proles. All legal foreign trade (almost all with China) is controlled by the state. It could, if it so chose, open up to China & Russia. It refuses to.