It's a worthy task, and the key to doing so is getting China on board. On one hand, NK is probably the most exasperating "ally" China has, but on the other hand

It's a worthy task, and the key to doing so is getting China on board. On one hand, NK is probably the most exasperating "ally" China has, but on the other hand, China really doesn't want the combination of refugees and US bases on its borders in the event the government collapses. So perhaps a deal where North Korea becomes a Chinese SAR for a period of 25-50 years (since China is much better prepared to absorb the cost than South Korea)?