It took hundreds of years for the whole of Europe to transition through the stages of feudalism, leading up to its political overthrow and replacement with bourgeoise democracies, whether true republics or consitutional monarchies. The first European republic, France, was even defeated by a coalition of monarchies and had its royalty restored! But that didn’t change the gradual transition of economic forces that lead inescapably to the political dominance of the capitalist class. The monarchies of Europe didn’t lose their power all at once, but as the capitalist class gained power they flipped one by one, or else had the actual political power of their aristocracy quietly stripped away. Thus it is with capitalist republics across the world today. Over perhaps hundreds of years, capitalist republics will become socialist, some socialist projects will be overthrown by coalitions of capitalists the way France was (e.g. the Paris Commune, the USSR, Yugoslavia) but as the capitalist economy was superior to the feudal economy in terms of industrial output - even in countries that still had a monarchy, like the German or British Empires - so the socialist centrally-planned economy is superior to the capitalist one, even when there are still markets present, which will eventually lead to global political domination by the working class. After the last capitalist republic has been overthrown, and the working class has fully eliminated capitalist ownership, hence the capitalist class, hence competing class interests entirely, then the structures and organizations required for that task can be decomissioned, some kind of borderless world government can be instituted, all economic activity can be directed for the fulfillment of needs, etc. And probably, in regions far from the front lines and risks of capitalist sabotage, such conditions would probably already be well-established in practice. But it could take another one or two hundred years to reach that point.