> edit: I will stand by my comment. Lets see how many 70's and 80s era houses last until 2040.

2040 is only 17 years away! Houses from the 1970's and 1980's are selling for top dollar today in suburbs all over North America, if the expected life spans of those structures were only 17 years they'd be worthless.

Where I am from the late 60's and early 70's homes are the worst quality ones on the markets, really a terrible time for home building. The issues are all foundations, plumbing, and wiring.