China's GDP is around USD18T, Export is around 4T and to the USA, about 500b which is less than 3% of their total GDP. Will they be doomed because they lost 3% of their GDP? Is it realistic to assume they will lose the entire 3% in a trade war?
The US cannot possibly make those 500b goods themselves, it is just a matter of shifting the buying to some other countries who may still be buying the materials and components from China.
As much as the US is a big market, its export value is also not small. It stands at around 3T vs 3.8T imports. If the US wanted to start a trade war with everyone, a huge chunk of their 3T export would also be impacted. Their only eyesore is that the bulk of their deficit is with China, but unless they start making toys, shoes, clothing and other low-value goods themselves, their 800b deficit will not disappear just because of tariffs.
https://www.statista.com/statistics/252246/total-value-of-us-international-trade/