I agree that North Korea keeping up with it´s current behavior is dangerous, it´s just far from clear whether a regime collapse would make things better or worse. The safest solution might be something like a soft collapse where the Kims and their friends are offered a safe retirement in China en exchange for stepping down and letting South Korea and/or Soutj Korea take over (which is unlikely unless China is threatening military action otherwise - and since China does't want Japan to go Nuclear, it has an incentive of finding some way to calm down the Kims).