The median annual income for people over age 65 in the United States is only $18,000, including public assistance and financial help from friends and family. The average—skewed upward by the highest incomes—is almost $29,000.

Vanguard analysts put the chance of a double-dip recession at about 20%. The bond yield curve suggests only a 6% risk, but the yield curve isn't as reliably predictive as it used to be, they say.

Issuers of variable annuities with income benefits could face lower-than-expected lapse rates and higher reserve requirements over the next 18 months, says Oliver Wyman.