I am glad Steve is writing about this. It is important that we recognize the likely resistance that will occur if the Kim Family Regime collapses (and very similar conditions will exist in post-conflict after the regime is destroyed).
My work on this can be found here:
"Unification Options and Scenarios: Assisting a Resistance" (2015)
"Should The United States Support Korean Unification: And If So, How?" (2014)
"Thoughts on Irregular Threats for north Korea Post-Conflict and Post-Collapse: Understanding Them to Counter Them" (2010)
I would say this to Steve (and anyone else who cares about this): The war, regime collapse, post-conflict, and post-collapse operations will be the biggest "by, with, and through" operation in which the US has ever participated. We owe it to our blood ally (and to the American people) to help them lead their own unification process but not lead it ourselves. north Korea is not Iraq and Afghanistan and the ROK military and ROK government is not the Afghan and Iraq military and government. We cannot approach the north Korea problem the same way we have Afghanistan and Iraq even though the conditions, conflict, and resistance will likely be far worse in north Korea than anything we have encountered in Iraq and Afghanistan (or Syria - and there are lessons there to be learned with the great and medium power interventions). We are going to have to enable and assist our much more capable partner and blood ally the ROK. But we cannot occupy the north with US forces and we cannot take the lead in the stabilization and unification process. If we do we will create a quagmire that will be far worse than the quagmire we have in Afghanistan, Iraq, and Syria and far worse than the one in which the ROK will find itself if they are leading and we are assisting (but it will be a quagmire nonetheless).