Food for thought.
As a retired childless person of a certain ahem, age (oldie), I am living in the house and area that I am very happy in. Mortgage paid, and utilities are minimal really. I have a car, but if I didn't, everything is within easy reach by taxi, bus, tram. That includes hospital, doctor, dentist, pharmacy, and so on.
I thought it through when I took early retirement, and got all the big construction jobs done then, kitchen, bathroom (wetroom shower), new heating system etc. Made the house low maintenance, got rid of the clutter, got a chap in to do the garden who is still going strong etc.
It's an older house with only one bathroom upstairs. It's absolutely fine for me, but I am in the process of having a downstairs loo fitted. Putting in a shower area downstairs is not feasible without a very expensive extension, so that's not happening. I can use a chairlift if necessary to access the upstairs wetroom.
I have a room downstairs that is used for my hobbies and doing things on the desktop PC. That could easily convert to a bedroom if necessary on a temporary basis. If I am that unwell, I can live upstairs and make the boxroom into a little basic kitchen, the spare bedroom into a living room. All I'd have to do is slide down the stairs on my broomstick (chair lift) to get out for appointments if necessary.
If it got to the stage where I need a full time carer, well then I would prefer to use a halfway house place in a nursing home grounds instead. There is one near me, flats in the grounds, and when ga ga into the big house with you! I have EPOA in place, and DNR etc.
It is a very interesting thread, and I am sure there are things I haven't thought of yet!