On the other hand, because I live in rural Japan and am only really friends with the people who live near me, almost all of my friends are over 70 (I'm 50). While this is of course selection bias (as well as being anecdotal), people I associate with don't end up in nursing homes -- at least long term. A quick google search tells me that only between 2 and 5% of people over 65 live in nursing homes and that jives pretty well with my experience. Most people seem to live pretty well until a year or so before they die, and then they essentially fall off a cliff.

My wife's aunt passed away last year from some kind of brain issue (I never did figure out exactly what the problem was -- lack of vocabulary). She was in and out of the hospital for about 3 months and while distressing, I think she very much appreciated being alive in those 3 months. After that she essentially ended up in a kind of semi-coma where she was awake for maybe an hour a day -- and she was in a nursing home. After another 5 months or so she passed away. I don't know if she got much value from those 5 months, but I know her husband definitely was able to use the time to come to grips with the reality of the situation. Again, just an anecdote, but I think it's illustrative of the complexity of the situation.

Anyway, I think most people can look forward to enjoying their old age. Of course it makes a big difference if you look after your body when you are young and it is much easier to do so.