Then, design a type of self-governing community 'constitution' that would direct operation of the community by the community. An expanded home owners association of sorts.
The community would be funded by the social security income of the residents. All residents who are still able work in some capacity to offset the costs of operation. Those who are no longer able to work would still remain and be assisted by other members and skilled nurses.
Professional services such as legal and counseling can be provided on site. Perhaps add a medication dispensary.
A single community could have, I don't know, 1,000 people? The average social security benefit in 2019 is $1,461. This would yield a $17,500,000 annual budget for the community to operate [3].
This is a similar concept as a Kibbutz, which works as an organizing approach in Israel [1]. One difference is that this community would be primarily funded by social security receipts, rather than industrial or business activities. Many costs of operation can be offset by growing their own food, making their own beer and wine, doing their own maintenance, managing the finances using standard corporate control policies.
Such an arrangement would have all the opportunities that seniors need: Social engagement, valued work, friendships, privacy when they want it, people watching out for each other, a feeling of contributing.
More importantly, it would be available to seniors who hit retirement with no wealth, and no income other than their social security check. There are 25 million Americans in this situation today [2].
[1] https://en.wikipedia.org/wiki/Kibbutz
[2] https://www.ncoa.org/news/resources-for-reporters/get-the-fa...
[3] https://www.aarp.org/retirement/social-security/questions-an...