Here is an idea: China stock and housing crash. They can not afford to buy a single blue barrel of oil, nor an imperial ton of iron ore. What then? Money printing! Always smart. But their "peoples money" will not buy anything abroad. Then what? Use their stash of dollars. Sorry treasuries. Then what? Interest rate hike in treasuries. Yellens dream. Then what? Credit contraction....
Then the eventually of yours slowly but surely turns into the never of mine. There can be only one...
And that is the US dollar!
Then dollar printing... then stagflation ... then hyperinflation ... then a new world money system that fails...then bitcoin and gold.