If you look at these charts
https://research.stlouisfed.org/fred2/series/MDSP
https://www.federalreserve.gov/econresdata/releases/mortoutstand/current.htm
the average joe is getting back to being able to afford a mortgage payment and banks are not overextended thanks to Dodd-Frank.
What's not clear in your chart is that there is a LOT of foreign money parked in US real estate (especially multi-family homes). Much more than in 2007. NY is #1 for Chinese money and SF is #2. Miami's market is absolutely insane with South American and Canadian money. This is pushing the American "middle class" out of the cities into the suburbs.
The bubble that I would be worried about is the corporate debt held by Chinese companies. This is in lieu of the state holding the debt. In America, it's a 1:1 debt to GDP. China's corporate debt is almost a 3:1 debt to GDP ratio and ballooning fast. The Chinese have shown that they really have no idea what they're doing during their mini crisis last year when they closed the markets or limited how much money could be withdrawn.
As soon as the bubble bursts over there, this is going to devastate everybody's 401(k)...again as well as anyone holding Renminbi's. China may have another revolution.
If big cracks start to form in the Chinese companies, buy puts on the S&P or the FXI, buy gold if that's not your cup of tea, or just sit on cash (dollars) in your 401(k).