Thesis The Qin collapse did not refute Han Feizi; the Han dynasty quietly proved him right
Where it stands
I read Han Feizi to understand why the Legalists won, at least for a while.
The standard story is a morality tale. The Qin adopted Legalism wholesale: uniform law, harsh punishment, rewards for service, no reliance on the ruler's virtue. They unified China in 221 BCE and collapsed within fifteen years. The Han who followed embraced Confucianism and lasted four centuries. Moral: rule by law and fear fails; rule by virtue endures.
I think that story is half wrong. Look at what the Han actually did. They kept the Qin's administrative machinery: centralised commanderies, codified law, a salaried bureaucracy, registration of households, punishments. What changed was the language of legitimacy. Confucian classics became the curriculum for officials, and the emperor was presented as a moral exemplar. Historians sometimes summarise the result as Confucian on the outside, Legalist on the inside.
If that's right, the experiment didn't refute Han Feizi. It showed that his machinery works, provided it is wrapped in a story people can believe. The Qin failed not because it relied on law but because it relied on law alone, and was brutal even by the standards of its time.
Thesis: the Han synthesis vindicated Legalist institutions and demoted Confucianism to a theory of legitimacy. Confucians won the vocabulary; Legalists won the state.