One other factor that may help the U.S. is that America will have an easier time getting access to some resources as production ramps up than China given our excellent geographic position and China's lack of a blue water navy that can cut off American supply lines. However, while America's navy may get pushed back from the first island chain, there are several other chokepoints it can use to stop materials from coming in to China by sea (which is one of the only cost-effective ways to ship the amount of mass needed to produce war materiel at scale), and many of China's neighbors are not friendly to the CCP and not liable to support shipments of material to support a war through their territory even if it is economical to do so.