In 2029, for people 75 to 84 (ages when they’re likely to need long-term care), that would mean access to about $25,000 to $74,000 a year in current dollars. Over age 85, the middle-income category extends to $95,000.

About 14.4 million people will fall into the middle-income category , almost double the current number. Sixty percent will need canes, walkers or wheelchairs to remain mobile, the analysis estimated, and 20 percent will need extensive help with the so-called activities of daily living, such as bathing and dressing.

They’re a better educated and more diverse group of older adults than in the past, less likely to experience poverty. Still, most will be unable to afford assisted living, the authors found.

A decade hence, 80 percent of middle-income seniors will have less than $60,000 a year in income and assets, not including equity in their homes. Yet the estimated cost of assisted living plus out-of-pocket medical expenses will hit $62,000, by the team’s conservative estimate.

“This group gets ignored and underserved in today’s long-term care market, and it’s a problem that’s going to explode over the next 20 years,” said Caroline Pearson, a health researcher at Norc (formerly the National Opinion Research Center) at the University of Chicago and lead author of the study. “When you see the numbers, it’s sobering.”

Depending on how one defines the need, half to two-thirds of older Americans will eventually require long-term care.

Like Ms. Harris, many consider selling their homes to finance it. (The analysis includes assisted and independent living but omits nursing homes, where Medicaid becomes a major payer.)