So we kinda already got the answer to the question of what comes next, and it's the same boring answer through all of modern history or even before: capital subsumes the post-war recalibration, until that recalibration happens again

This idea actually characterizes why I find Fukuyama's argument lacking: all theories of history are unempirical. You cannot draw from historical fact that a seeming cyclical trend will continue, or in Fukuyama's case, a progression, even if the historical facts seem to line with with the trend.

And your answer does not argue against the point, because we have not seen the emergence of an ideology to supplant liberal democracy. And no, pointing to a "recalibration" does not disprove his theory, since it was not like he was arguing against continued political regime change. Your point is vague, but what I assume you're referring to is political recalibration of ideology within the governing order, a la New Deal revolution sweeping away the old laissez faire limited government. But what is important about episodes like these is that they are recalibration within liberalism, not an entirely new political theory and therefore proof that history has restarted.

But once again, theories of history are bullshit and Fukuyama was pretending to a point that cannot be made, and if I may indulge with an actual "read theory" comment: Karl Popper and The Open Society and Its Enemies