It's already happening. Due to changes in the way the CPI was calculated during Clinton's tenure, inflation is understated, so Social Security COLAs are understated as well. If you're one percent low per year, that negatively compounds. By 2020, if current trends continue, Social Security benefits will probably be only about 50-60 percent of their 1992 equivalent value. And that is about what the system can provide since there is no SS Trust Fund with real assets.