Earlier quoted context omitted.
The PRC is estimated to have some 350 warheads, enough to land one or two on every US city of 100k population or more, killing about a third of the population. That's not nearly enough to prevent a retaliatory strike, but it seems like a fairly effective deterrent, and Intel's and TI's US fabs would definitely be out of commission, even if they weren't targets, until after the Mexican Army or whoever moved in to mop…
China was ruled by rival warlords far more recently than 2,500 years ago, most recently from about 1916 to 1928 (officially, though some warlords continued to hold sway in isolated regions well into the 1940s). Strong central government collapses -> country fractures into regions controlled by warlords -> new strong central government arises. China has seen that movie many, many times in its history.
Similarly, when the strong central government in Mycenaean Greece collapsed in the Bronze Age Collapse, Greece fractured into "regions controlled by warlords." Then one of those warlords, Alexandros, conquered Persia, most of the Mediterranean, Turkey, much what is now Uzbekistan and Turkmenistan, and part of India. Then he died, and his empire fractured into regions controlled by warlords. Then the Roman Republic conquered most of the same region (not coincidentally becoming a Greek-speaking empire in the process), plus part of Britain and most of Western Europe, and fractured into regions controlled by warlords. Then the Holy Roman Empire arose and reunified a lot of those regions, at least in name (arguably, much like the later Zhou) and then fractured into regions controlled by warlords. Then Napoleon arose and reunified a lot of those regions, including parts of Russia that Rome and the Holy Roman Empire had never reached, but that didn't last long, and the warlords retook control from Napoleon pretty quickly. Even the Bourbons got restored! Then Hitler arose and reunified a lot of those regions, but his "country" fractured into regions controlled by warlords even more quickly. Then the European Union arose and reunified a lot of those same regions again by winning the loyalty of local warlords like Charles de Gaulle, Paul-Henri Spaak, and Joseph Luns. Or, alternatively, NATO did. Or the UN.
And you can tell a similar story about Russia.
You could reasonably object that NATO, the EU, the UN, and the Holy Roman Empire aren't or weren't "strong central governments" as we know them today. Well, they weren't Westphalian states, it's true. But neither were any of the reigns of Chinese emperors we're talking about here. And, although if you go to overseas Chinese school you might be taught a simple linear succession of dynasties, the truth in China is much more complicated, just as the truth about western Europe is much more complicated than my linear version above.
What does that have to do with what Russia would do if the nukes started flying? Does the collapse of the Kievan Rus' in the face of the Golden Horde mean that Russia's command structure would collapse in the 20 minutes needed to launch a counterattack? The Scythian king Ateas, from what is now Russia, fought in his dotage and fell in battle with Philip of Macedon in 00339 BCE, and his empire collapsed. Should we thus infer that his successor Vladimir Putin will remain in power too long and make Russia weak, easy pickings for a new conqueror?
Such inferences are obviously ridiculous.