NEW YORK (AdAge.com) -- The current downturn in consumer spending is actually the beginning of a 15-to-20-year period of lower consumer spending in general across the U.S. That's according to Mark Zandi, chief economist for Moody's Economy.com. He was looking into his crystal ball for attendees at the National Retail Federation Convention and Expo in Manhattan. He predicted the retail industry would be forced to adjust to new long-term market realities through cost-cutting and downsizing.