The American Society of Interior Designers has created a report called Home for a Lifetime: Interior Design for Active Aging. It notes:
As longevity increases, so will the likelihood of chronic health conditions and the need for regular assistance. Studies show that elderly Americans are reducing their use of nursing home care, in part because they prefer home delivered care or assisted living. They will need a suitable and accessible place to live, whether they remain in their own homes or live with a family member.
The report provides a comprehensive set of considerations for designing spaces that promote aging in place. Apparently, a lot of it has to do with what you raise and what you lower. Things to be raised include toilet seats and lighting levels; things to be lowered include beds and light switches.