I lost my dad about 19 years ago to a brain tumor. My mom is 83 and lives in a house she bought right next door to us. She moved here from out-of-state five years ago and we have never (well almost never) regretted that. Aside from asthma, she is in decent health and still drives to her doctors and to get groceries, etc. She cooks for me every evening (or I bring home takeout) and is sharp as a tack mentally, but slowing down a lot physically. Caring for me and her cat seems to give her continuity and a sense of purpose in life. For the moment, my most serious challenge is giving sufficient attention to both spouse and mother.
When mom slows down more seriously, we should be pretty well situated to take care of most of her needs. That is the hope anyway... but there are things we cannot control of course.