A 20 year retirement on the back of 35 years of working means dying before you're 80?

Given current life expectancy, and particularly if you find a life partner, the chances of at least one of you surviving through at least 85 are pretty high (like above 60% for the US).

I assumed that a "real" career and substantial savings, after paying off debt, begin at age 30. And the 20 year retirement was me being conservative. In truth, saving only 20% of your take-home for 35 years will be more than enough for 40 years.