Sept 27 (Reuters) - Chicago Federal Reserve Bank President Charles Evans on Monday said he expects U.S. unemployment to fall below 4% “before too long,” but even a drop to 3.5% would likely not be enough to drive inflation sustainably above 2%. “I don’t see the upward inflation risks unless something gets out of hand,” Evans told the National Association for Business Economics. It’s still “early days” to think that recent high inflation readings due to bottlenecks will work their way into inflation expectations , he said. (Reporting by Ann Saphir)