In 1980, the US economy was more than 10 times larger than China’s, yet by 2017, China with its rapid growth could have the largest share of global GDP, more than 18 percent, according to International Monetary Fund projections. US leaders have not prepared their citizens for this “great convergence,” suggests Kishore Mahbubani, author and dean of Lee Kuan Yew School of Public Policy. Still, much...