Capitalism is the ultimate conqueror, because it has nothing to defend. Tethered to no principle, place or people, it is infinitely adaptable. It thrives under nationalism as well as revolution (as in the triumphant anti-nationalist revolutionary phase we're in now), in peace as well as chaos. It's less a system of integrated parts than it is aggregated behavior establishing economic hierarchies. These hierarchies can be overturned, wealth can be transferred (at great destruction here, great profit there), but the "system" churns on and through its platforms, barely perturbed.
Its putative opposite, communism, could adapt only at risk. Capitalism is "threatened" by "excessive" government control, commerce can be stifled with regulation and entire nations beggared by bad policy, but capitalism thrives without and floods back in the moment legal, social or political barriers are taken out of its way. Communism trying to adopt a bit of capitalism ends up untenable, as in the Soviet Union, or a nominal farce, as in China. In the social democracies of Europe socialism has long needed capitalism more than capitalism needs it. Capitalism needs more consuming humans there. Capitalism needs migration. Socialism complies, has at hand, conveniently enough, the identity politics which it now wages against the interests of traditional labor. The old working class hero hasn't just been replaced; he's now the heavy, and in our electronic equivalent of the old Soviet posters of heroic working folk he's been pasted over by Minorities, Women and Gays.
But it seems we're running out of principles and people to sacrifice to capitalism.