The gap's always been there. And, of course, you'd have to examine how the figures are obtained. Many people- most people - save for retirement in their own way. Chief today is buying a home, upgrading, moving up in the market over the years, then downsizing upon retirement to pocket the difference. Others have funds in non-examinable items like gold or silver or various collectibles. And cash. It is a mug's game to come out and state-the gap is widening! Foolish.
But the nature of the common pension plan is changing. The best plan - defined benefit - is under pressure. This plan guarantees a recipient a set amount according to a promised formula and inflation protection. Can't beat that!
Other plans are more stingy but often offer benefits. Quite a carrot and one the number crunchers aren't putting into their calculations when declaring a gap.
Economics education isn't a strength of reporters or survey gatherers. I wouldn't get too concerned.