If I was designing a retirement place, I'd make it a small village.
There would be 2-bedroomed houses for those that wanted them, to buy. Ownership of one would automatically qualify for a regrading into a flat, when needed, closer to facilities (restaurant, cafe, pool, communal area, laundry, exercise/gym area) and then, when/if independant living becomes impossible into a supported living area with qualified care staff in hand.
It would, of course mean, you'd need to be able to afford this in the first place and your first bought property under the scheme would be used to pay for later moves or care, but it would remove the onus from children (though they'd lose out on some of their 'inheritance') but it could mean continued contact and support from friends made within this community.