Can't we all accept the World is not going to end.... Old people die, Presidents, Kings and Queens get deposed or replaced.
North Korean President dies... North Korea fears outside forces will take advantage, they step up security. Adjoining countries see the movements and instantly fear a possibility of an invasion... They raise their security. We then see other countries watching this activity and they in turn start hitting the panic\reaction button. Has this ever happened before? Think President Kennedy.
Why not just sit back, let North Korea mourn and replace its leader... Simples