Have you discussed this with your parents and inlaws? When they are too old to live alone, where will your parents/inlaws go?
-Will they live with you?
-A sibling?
-nursing home?
-fancy assisted living community?
Have you talked about it with them or your siblings?
I think DH would have either/both of his parents live with us in a second. I would push for a big house or a house with a "mil suite" at that point.
I think my own mom would prefer to live alone with maybe a nurse coming during the day. My Granddad is 93 and still lives alone but has a nurse come during the day and my aunt lives next door and he has an alarm to ring her if he needs it.