The United Nations would like the dollar, euro, yen, and other national currencies to be succeeded by a new "global currency." That recommendation appears in a U.N. report released this week, which suggests the dollar's outsize role in international finance has ended -- and says that it's time to invent a successor currency that would be managed by a "Global Reserve Bank." Countries could "agree to exchange their own currencies for the new currency, so that the global currency would be backed...