I don't have specific advice for the original question. But I have been exceedingly happy with what my own parents have done, they're both in their early 70s.
During the last 10 years, all 4 of my grandparents have passed away. They lived long good lives, and did my parents the service of "taking turns". Though one had 3 kids and the other 6, it fell to my parents to do the majority of the work during each's final years due to many issues, geography being one. It was a LOT of work for my parents. Many times they joked that, just when they got the kids out of the house and on their own, it was time to start taking care of grandma and grandpa.
Having been through that, my parents have taken some steps to avoid some of the pitfalls they experienced. Once a year, we have a family dinner (us and their children + spouses). It's usually a sort of joint anniversary dinner. And after dinner, we have a "state of the union" type chat. At least an hour or more. Our parents talk about how they're doing, how their finances are doing, how their health is doing, even their mental health, what's bumming that out, etc. We ask questions. It's all very candid.
This discussion is never had without everyone present. My Mom's explanation is that she doesn't want there to be any sort of "well, when I was talking to Mom she said, and what I think she'd want is..." There won't be arguments about when or if to put them in a nursing home. We know how they want to be buried. Kind of service, etc.
There will, I'm sure, be surprises and we'll have to adapt. But we've tried, and it's a together effort, because they kicked the ball off that way. Before it was too late to have these discussions. Their biggest frustration with their own parents had been that they didn't want to talk about it, and when it came time to have to talk about it, it was too late. People's faculties and emotions were compromised at that point.
My wife and I have compared this to her parents who are in their late 80's. It's going to be a mess. They won't talk about it. Don't want to. It's uncomfortable. And the kids all have their own viewpoints on thing.
If you can, before it's too late, start having the candid discussions now, together as a group. It makes things way better in dealing with the downhill years.