I find it unlikely that the regime would survive if the leader was taken out in public fashion. The Kims maintain control of the country via a cult-like aura of invincibility. The likely situation is the military taking control in the immediate aftermath and pulling an Egypt - some mild liberalizations to protect the new order, while maintaining the general status quo. I think you'd see less exercises of paranoid, brutal authority and more standard dictator tactics.
The Organization and Guidance Department (OGD) of the Korean Workers Party has been the backbone of the regime for decades. There is no reason to think they would lose control to the Army in this scenario.
It would be the military that had failed to protect the dear leader, so they are the ones losing prestige.