Perhaps. There are other ways to render them useless. But that would require destabilizing the NK leadership, and we would never destabilize a foreign government...
North Korean military brass become rulers of various city/regional fiefdoms this wealth and power gives them incentive to go along with the plan.
South Korean and Chinese businesses get access to cheap and incredibly compliant labor, and the new markets these newly paid workers represent.
Even at minimal labor rates the typical North Korean peasant rapidly becomes wealthy beyond their wildest imagination. More food than they could ever have seen, better clothes, warmer houses, bicycles, motor scooters and perhaps even a (Hyundai or Kia) car.
And even with a minimal skim the former Brass could live like gods. If they play their cards right, tie themselves to the prosperity in the peoples' eyes they could be much loved and politically successful.
Little Kim could even survive the transition if he gets ahead of it and is seen as a savior, but more likely he'll end like Benny the Moose or Ceaușescu, reunification or no.