My mother is 98, and has been in some type of care facility for 10 years, the last 5 of which is a full care nursing home. She is the oldest resident there, and also holds the longest residency title. Most in a nursing home last 2-3 years. she's outlived five roommates. She has senile dementia, is in a wheelchair, and is/was impossible for my sisters and me to care for at home. She has, of late, become almost unresponsive, but still eats well, and continues to live. she has a strong constitution, but on a 1-10 scale, her quality of life is in negative numbers.
Five years ago, she was pleading with us to let her die, but her condition has gotten us past that. She was a caregiver for a couple of older aunts before they had to go to homes, and this was the LAST thing she envisioned for herself. She would have gladly opted for some merciful exit, had it been her choice. We have all the legal documents in place so that there will never be a question when/if we get to the feeding tube/machines stage, but now, we're all just waiting and enduring....
Fortunately, my father made some wise stock decisions years ago that allow us to maintain her despite the expense. (Exxon) She will probably eventually run through it all, which is a shame, because one of my sisters could use the money.