Let's assume the many worlds hypothesis is correct and consider all of the branches of the multiverse that share our 1946. In how many of them did the cold war turn hot? For what percentage would it have been better to make the threat?

Given that a massive amount of quantum-scale randomness would have to go systematically in a different direction for it to have any noticeable macro-scale effect, and that even then most macro-scale effects would be barely even noticeable, isn't the default answer to questions like this always "in the overwhelming majority of branches, history never noticeably diverged from ours"?