The Successor to Greenspan Has a Very Tough Act to Follow WHEN Alan Greenspan finally retires from the Federal Reserve, will he leave behind any of his DNA? Now in his 18th remarkable year as Fed chairman, the owlish and idiosyncratic Mr. Greenspan is required by law to step down in January 2006. Nominating a successor could be President Bush's biggest economic decision next year, given Mr. Greenspan's mythic reputation as the guardian of price stability and economic growth. A big uncertainty is how any successor will extend Mr. Greenspan's approach to monetary policy, which has been as much an...