In his new book, Arvind Subramanian presents the following possibilities: What if, contrary to common belief, China's economic dominance is a present-day reality rather than a faraway possibility? What if the renminbi's takeover of the dollar as the world's reserve currency is not decades, but mere years, away? And what if the United States's economic preeminence is not, as many economists and policymakers would like to believe, in its own hands,...