Even among the affluent, 80 is the new 65. Nearly one in five with assets between $100,000 and $250,000 feel they will need to work until "at least age 80." Among all the affluent, 12% said they will work until 80 years of age. In the survey, Americans had to have investable assets of $100,000, excluding real estate and other property, to be considered affluent. The group surveyed was split evenly between Americans with between $100,000 and $250,000 and those with more than $250,000. --Written by Christina Cheddar Berk of CNBC.