When my dad was at a stage of life where he couldn't be left alone, we considered a domiciliary – that's what it was called in Montgomery, AL. It was a home that had elderly folks who could move about, feed themselves, dress, keep their room, etc. There was a cook and an administrator/nurse type person.
I think keeping them active is a BIG factor of how well they are physically and mentally. It would be great to have more of these types of places around the country. I'm sure somebody would have to “administrate” since having so many families trying to come to agreements on expenses, etc. would be quite the challenge.