Few events are potentially as destabilising for undemocratic regimes as the unexpected death of the supreme leader. As the number of totalitarian countries in the world has – mercifully – declined, so too has this understanding. But it was revived yesterday with a vengeance, after the announcement from Pyongyang that the Dear Leader, Kim Jong-il, had died suddenly while travelling outside the North Korean capital on his special train.

There is not a little irony here. One of the few facts known about this reclusive individual was that he avoided flying. In August, he made his second journey to Moscow by rail. This aversion limited his contact with the outside world, even if – for which there is not the slightest evidence – he had any interest in foreign relations. There are also two circumstances that may mitigate the immediate repercussions of Kim's early death, at least domestically.

The first is the relative speed of the announcement. Kim's death had been rumoured before, with foreign observers generally accepting that his demise would not necessarily be made public until his absence became too embarrassing. In the event, the authorities seem to have calculated that even North Korea's isolation was not such that they could risk the protracted circulation of – this time – well-founded rumours. The second is that Kim appeared to be making early preparations for the succession, when he promoted his younger son, Kim Jong-un, to the rank of four-star general a year ago and allotted him a more prominent role in state affairs.

The assumption is that Kim Jong-un will succeed his father, as indeed Kim Jong-il succeeded his – making North Korea one of the world's more durable non-monarchic hereditary dictatorships. The latest Kim, though, is still in his 20s and untested in power, which hardly bodes well for surviving the storms and rivalries that may lie ahead.

Yet it has to be asked whether stability, at least in the sense of more of the same, is what North Korea needs or what its people – for all their shows of shocked grief yesterday – really want. Isolated, impoverished and at times near starvation, they have been kept in thrall to the past, as their leaders have directed the country's meagre resources to the military. The contrast between the barren North and the prospering South is itself an indictment of the regime in Pyongyang.

How far the nuclear warheads it has developed are actually serviceable is a moot point. But unreliable weapons in the hands of a nervous and inexperienced leader make for a lethal mix. The North has launched small-scale conventional attacks on southern interests twice in the past year, bringing the two states to the brink of all-out war. It is no wonder the prevailing response to Kim's death in the region and beyond was extreme caution, and in the South the declaration of a military alert.

Any hint of change in North Korea inevitably sets not only the South, but Japan, China, Russia and the United States on edge. And, with China contemplating its own spasms of unrest, the whole region suddenly looks less stable than it did. In Seoul, that naturally fuels fears of border breaches, a refugee crisis, even a full-scale military attack. But change should also, however tentatively, fuel hope: hope that the next Kim might try to make the North a better place to live, with reunification – not necessarily through violence – further down the line. Not all change is necessarily bad.

Twenty years ago, the world was reflecting on the imminent end of the Soviet Union. This year has witnessed autocracies toppled or shaken across North Africa and the Middle East. Through all this time, North-east Asia, despite its latent tensions, has seemed a zone of relative calm. For better or worse, that can no longer be taken for granted.