As Yogthos notes, while it could badly hurt the US, it would also advance its plans of decoupling as it would force the matter in a hard, hard way.

The US including capitalists who have been happy to continue profiting from business with China and have resisted moving operations elsewhere would at that point have no choice but to begin investing heavily in India and a few other countries as well as some in the US to get the economy going again. I suppose they could just sit on their money and do nothing but as long as the US can print infinite money the US government could just step in and I'm sure the Indian bourgeoisie and government would be happy to quickly set aside a large sum of money to help with this.

Though in a way it may not be China's choice and inevitable. They keep talking about decoupling and may be set on it. They can instigate a war with China over Taiwan, slap sanctions that amount to a blockade and near total cutting of trade on China and at that point have achieved decoupling anyways and do so at their own pace to let their companies and consumers down gradually by winding down trade in a fast but more controlled way that benefits them. So there is an argument for China decoupling on its own terms and timetable rather than on the terms and timetable of the US to be sure.

On the other hand neither we nor the US government planners nor China can be sure the US bourgeoisie would actually go along with such a decoupling. They may simply not allow it, they may refuse, continue trade and dare the US to do something which it probably won't if enough big bourgeois corporate interests just ignore them or route around it via importing via third parties. So that's an argument for keeping the capitalists of the US glued to China's side.