The case for not paying off your mortgage by retirement - The Washington Post

Anderson, author of “The Value of Debt in Retirement,” says people should think more like corporations by balancing debt with the cash they have on hand. While some debt should be paid off as soon as possible, he says, not all debt is bad.
http://www.washingtonpost.com/news/get-there/wp/2015/03/26/the-case-for-not-paying-off-your-mortgage-by-retirement/