The IMF in its analysis looks beyond exchange rates to the true, real terms picture of the economies using “purchasing power parities.” That compares what people earn and spend in real terms in their domestic economies.
Under PPP, the Chinese economy will expand from $11.2 trillion this year to $19 trillion in 2016. Meanwhile the U.S. economy will rise from $15.2 trillion to $18.8 trillion. That would take America’s share of the world output down to 17.7%, the lowest in modern times. China’s would reach 18%, and is rising.
Just 10 years ago, the U.S. economy was three times the size of China’s.
The Pax Americana has been based on America’s economic as well as military supremacy. Our economic model provided an example to all that free markets are the way to grow your economy, and our military supremacy maintained a relative sense of order. The US Navy, and in more modern times the Air Force, were never far enough away for rogue states to be too comfortable acting up. Along with the US economic model and the military, American culture advanced across the world. The Age of China, if we’re truly entering that in about five years, will be a very different world from the one we have known for the past 120-odd years. The Chinese economic model is basically fascist — state control of industry with some leeway for decision-making within industry — and its cultural model is strongly collectivist. Its economic model will be adopted by others, or exported by force, as will its culture (Firefly may turn out to have been more of a prophecy than a TV show). China’s tendency to let rogue states act with impunity as long as their actions are useful to China (North Korea, Iran) or irrelevant to China’s interests (Libya, pretty much everywhere else) signals that should China assume the global leadership role, the level of world chaos will rise quite a bit.
The hard left has long railed at the “evil” of various US policies and tendencies. They may get the chance to see how one of their favorite countries behaves as the global power. They’re unlikely to like it.