you can't be serious...almost anything you eat (though to a lesser degree than others that follow), wear, use at work, use in your leasure time, your car, your house, your everything is made of Chinese ingredients or finished products.
China is not as developed as the US with it's numerous trading partners and power to enforce trading relationships. Given China's actual importance in producing goods that we all use, they really do have to stockpile. Commodity shortages would produce much more damage in a less diversified economy. As for the US, we actually have a 50 year oil reserve. As if we weren't a ("the"?) top exporter of oil already along with several key commodities. Who the heck in America eats soybeans or ginseng root? Also, the key Chinese industries that serve the world are very dependent on commodity inputs. Compare that to the US's service based industries.
In history, everything changes, all at once, all over the world. This game is rapidly changing and I don't pretend to know what the heck the next cycle is going to look like. If history is any lesson, you can't project America's decline or China's rise out into the future. I'd be surprised if there were only one America or one China 50 years from now.