If America goes home China's rise is quickly OVER, without anyone providing global trade security on the open oceans. This would drive unrest internally, and over the last 1500 years when China's central control has been threatened, they have turned inward and become shut ins.

The Belt and Road is partially an attempt to deal with the risk of the US pulling out of providing global security, but they need a LOT more time, and somewhat ironically because of COVID-19 they may have run out. While the US is spending trillions to move away from global trade very very quickly.