North Korea has long been an annoyance for both the United States, and also their more prosperous neighbors to the South or their country. Largely due to the strange ideologies of their leader Kim Jong Il, many people in north Korea are faced with a struggle to survive on a day to day basis
The first scenario for the eventual fate of North Korea is that a second Korean war is provoked by North Korea's actions. Largely fuelled by his own paranoia, Kim Jong seems to be under the impression that the South along with their allies the United States are poised to invade, and keeps a large military constantly ready for action. He also seems set on scaring the west into leaving him alone by claiming to have developed nuclear weapons, although this doesn't seem to be the case.
Although the development of nuclear weapons has been claimed by North Korea in the past, in actual fact recent 'nuclear tests' were found out to be nothing more than large quantities of explosives. Posturing and bluffing can only go so far in provoking intervention, although it would only take the continued derangement of their leader to make the North attack first. As Kim's health fails and his country threatens to fall into anarchy, he might just get desperate or oblivious enough to provoke a second Korean war. World war three isn't completely out of the question, particularly if China chooses to aid the North again, although more likely both China and the United States will want to keep fighting to the Korean peninsula only. A case of both having too much to lose over the actions of a madman.
The second scenario following the demise of Kim Jong IL is that his leadership will simply be transferred to either one of his relatives, or one of the stronger members of his government. Often when dictators die without a clear choice for leadership the state will fall into disarray, or even civil war. There isn't any real threat of civil war seemingly here however as there is no opposition to the regime. The higher up figures within the North Korean army could take command however, and could easily overthrow the rest of the regime if they had a mind to. Unlike the rest of the population however, the army has always been well cared for, and no coups have been reported so far in the region.
The third, and eventually inevitable outcome for North Korea seems to be that the regime as we know it will fail, and a new type of government will eventually be set up. Certainly the common people, as well as the international community would try to make this happen if the circumstances were right. Whether the country would again unite with South Korea isn't clear anymore, as the South would surely struggle to integrate the technologically backward and undeveloped North. At one time the reuniting of the two countries seemed like the natural thing to do, although now this isn't necessarily the case.
Whatever happens in North Korea, it is becoming clear that the kind of regime Kim Jong Il has operated is clearly a thing of the past. There are fewer pseudo-communist states than there were when the North first separated, and less support for their doctrines. Perhaps more tellingly, none of the powers of the world, namely the United States, China, India, Russia and the European States, are now under the kind of government that could afford to publicly support a regime such as this in the future.