I’m not super well versed on the financial interactions between the US and Cjina, but I imagine the total US change will be a washout. The financial markets will dip for sure since many US based companies do massive amounts of business in China, but a Chinese stagnation will also drop the bottom out of the prices in all of the commodity markets that drive a lot of price inflation in the US. Cheaper US industrial/energy inputs means inflation drops and consumer spending/corporate capex can increase.
That’s just a guess though, because China had also been rapidly developing ties to every other country outside of the West-centric financial bubble, and if those countries also see a contraction in Chinese investment, it could snowball a bit.