Some folks are building “intentional” communities that have mixed ages and everyone does some of the work for the group, like modern day co-ops of years before. When the buildings are new and folks are fairly healthy, that sounds like it could work pretty well. As the buildings and people age and more help is needed, they have to be sure there is enough capital on hand and enough help for people who need more assistance. Sorry, wish there were more and better answers.
We are hoping that as we need it, we can hire some visiting nurse and chef to come and service a bunch of our homes all together, since so many of us in this neighborhood are all aging–60s-90s.