I think behind the scenes China has already written off assets in the US, and even in other Western countries.IP? Commercial buildings? Investment shares?
Where do you think the billions in FDI from the US is going in China, it's just free money? It just disappears? They smoke it all?
Considering China has effective capital controls, I believe China does not need to and will not nationalise US assets in China, as a way to show the world that China is fair and respects commercial agreements, which would foster and attract more investments and business from other countries, isolating the US in the process.