Potemkin wrote:Nationalism is utterly incapable of resolving the internal contradictions thrown up by capitalism in its current stage of development. What answers does it have? Autarchy? Tarriffs? Mercantilism? Aggressive wars of conquest? Been there, tried that, didn't work. Nationalism, in its traditional sense, died in 1945 and the capitalist elite have no interest in reviving it. Endless national rivalries, destructive wars and genocides and economic autarchy hold little or no appeal for most of the population either. No, some form of internationalism is the future- either capitalist globalisation under the control of a tiny oligarchic elite, or internationalist socialism under the control of the working people themselves. History has no reverse gear.
First of all there's no reason to believe communism is going to resolve social contradictions that generate conflict and a local state to manage them. Men and women are different, IQ causes stratification in wealth accumulation, and different ethnic groups have different relationships to the land and tradition which cause them to treat the rest of humanity different. Inequality is an inevitable fact of life and not desirable to abolish, just erode. Beyond a certain point in erosion equality turns into equity and justice turns into rent-seeking behavior, at which point turning on the left is legitimate to preserve a functional balance. This balance is closer to a social form of capitalism, which will almost always be intrinsically nationalist, than communism where the prescriptions are so precise that deviation makes the project state capitalist.
Nationalism is never going to die because your idea of historical progress is absurd in how black and white it is. There will never be a situation like you want it, where there is just this world economy of global capital and global labor. You will always have that middle class in between which forms the basis for localism, integralism, and group self-determination as an alternative to either international socialism or abject plutocracy. We will always have a national bourgeoisie, a middle class, and a native working class. They will always be sooner tempted to form a political compact led by the combined spirit of a latter two to preserve social capital, a way of life, and a culture which in turn entails a set of privileges for the native worker and the petty/local capitalist, which manifest as arbitrary divisions in the market. These are very human divisions which we can expect to always exist regardless of theories about material conditions not supporting them.
You should not believe that capitalism is ever going to make the world 100% ripe for socialism like you describe, and therefore you can never even come close to pronouncing nationalism dead. There's nothing about nature or reality that is so fine and without its messiness. Within those grey areas, and there'll be plenty, communists get btfo by nationalists every time. It'll be the first alternative turned before socialism, because your ideology is inhumane in its materialism and nobody seriously believes they have more in common with a prole on the other side of the world than their local boss. Class collaboration makes more sense and is more practical, and far more congruent with human evolutionary history and sociobiology which doesn't support class conflict behavior.
tl;dr you shouldn't speak in historical absolutes and the many grey areas left in between are the bases for nationalism because, between dystopian international capitalism and a commonly held world, only it is congruent with human nature. There's nothing about this that entails war or genocide either, these are products of badly delineated borders, unjust international orders in an old era of imperialism, and other expressions of a intermediary period between the old world and the modern that we don't need to worry about.