NEWPORT BEACH, Calif. -- Ben Bernanke, the chairman of the U.S. Federal Reserve, has said he probably won't serve another term when his current one expires this coming January. His decision to skip the Fed's annual conference in Jackson Hole, Wyo., this summer has only reinforced the view that he won't be coming back. But history has yet to issue its verdict on the world's most powerful central banker.Undoubtedly, Bernanke will be remembered as a bold policy leader who helped avoid a global depression by courageously taking the Fed into uncharted waters using highly experimental -- and highly risky -- policies. At the same time, he leaves his successor with a set of unprecedented and unresolved problems to contend with, from weaning the economy off life support to navigating the consequences of an unusually large balance sheet. And with so much uncertainty about the success of the Bernanke way, econ textbooks and quarterly unemployment figures just don't hold enough answers to how his stewardship of the U.S. economy will play itself out in the years ahead.