It looks like the end of an era for the U.S. dollar. In his new book “Our Dollar, Your Problem: An Insider’s View of Seven Turbulent Decades of Global Finance, and the Road Ahead,” Kenneth Rogoff looks back on the currency’s dominant run in global trade and central bank reserves for a host of other countries. Today, he argues, that lofty status is on the wane. “My thesis is that the U.S. dollar is about to get knocked down a couple pegs,” said Rogoff, a professor of economics and the Maurits C. ...