Janus Capital Management's Bill Gross says he's skeptical that real GDP growth can rise to 3 to 4 percent. Prior to that, Alan Krueger, a professor at Princeton University, says NAFTA has been positive for the U.S. Bob Doll, Nuveen's chief equity strategist, says the more restrictions enacted, the less efficient the economy will be. Jim Grant, editor of Grant's Interest Rate Observer, says he expects the U.S. to revert back to the 1970s' weak dollar policy. Finally, PIMCO's Scott Mather says investors are underpricing central bank action.