Commentators all generally agree that the nation-state as political actor on the world stage has declined since WWII. Organization such as the UN, the IMF, etc., but perhaps even more the global economy as independent from the political sphere, have contributed to this decline. One of the major critics against governments is that they are unable (or unwilling) to take steps that would reassert political control over the economy. Because of this inability/ unwillingness modern states are objects, not subjects, of the economy. European states are no exception, but we must add to these the European Union, which has taken a lot of the decision-making that formerly belonged to each state–albeit not in the most important domain such as foreign policy or the military, but this is another question.
Yet the nation-state as a concept is still viable: the United Nations, the European Union themselves are based on this principle. Perhaps more importantly, many conflicts these days involve a minority group within a larger country that demands autonomy or independence, in order to create a state for their own nation (Kosovo, Abkhazia, apalestine, the Tamil, even separatist revendications within Europe itself for example). This is all the more amazing because if all those who fought for independence were given an independent state, we would end up with a patchwork of thousands of small entities. This is obviously not possible, all the more so as independence does not mean the end of every trouble, far from it–how do we deal with the world economy, which in fact de facto limitsthe independence for which these people fight; how do we defend ourselves against potential aggressors, sometimes more powerful, etc.? Despite all these problems, many peoples today fight for their own states. The idea is that each nation has its own state so as to exist as a self-ruling entity.