Even after a bitter civil war and national collapse, a Chinese invasion would probably unite enough people to make said invasion more costly and any “victory” more pyrrhic anyone has managed in Afghanistan, or the Balkins, or any land war in Asia (never mind going against Sicilians when death is on the line).
Agreed.
I don't believe that the government of China has any interest in conquering the United States as an occupying military force. Why would they? Our economies are heavily intertwined, it is in China's best interest to continue to sell us container ships full of goods in exchange for money which they will use to build their empire in their own sphere of influence. China does not have an economic interest in the collapse of the United States. I suspect that China will continue to be an economic powerhouse providing goods and services to the world. As they develop, I expect them to shuffle much of the manufacturing off on the developing world, acting as middlemen and service providers to the US and Europe.
In the long term, I expect at some point China will become the largest economy and the center of the economic world will shift that direction. The US will still be around, but slowly decline and crumble, becoming less and less significant on the global stage as empires do. Much like the Great Britain - the worlds most advanced and richest economy in the 19th century. Great Britain wasn't conquered, it's government, people and culture still exist. But the empire crumbled and they became economically overshadowed by other world powers.
China won't invade the US with soldiers, because it doesn't need to in order to get what it wants.