I guess I'm not as shocked by marginally higher median dual-earner incomes when I consider the Law of Supply and Demand. Have people sought degrees in proportion to the new jobs demanding those degrees, or have people sought degrees in response to the higher wages reported by such degree holders at that time? If more the latter than the former, then one can consider the possibility that real wages have not grown much because there is an oversupply of degree holders relative to the demand of jobs actaully requiring those degrees.
As far as not boding well (presumably for the US economy?), I want to believe that excesses are eventually squeezed out of a free market. Academia has to be one of the most masterful case studies in marketing, ever. At some point, people will not be able to afford tuition, or rationally value the product at less than the retail price tag.
I don't see any endemic problem. People have made these choices (paying for tuition beyond their means, spending beyond their means, etc.) of their own free will, and they will continue to act in what they believe is their own best interest. Marketing is apparently quite effective. As a consumer (not a marketer), it embarrasses me. But as a partial-share business owner, I take it for what it is.
If a cause is too much (easy) credit, that can (and will) be worked out of the system as well.