@k_j As you noted, siblings aren't always best friends, and sometimes downright toxic for each other, and now there's bickering over care plans, possibly leading to worse outcomes for the patient. That's not even thinking about what if the kids move away, can't be there for a parents care, hell what if the kids don't even like their parents. It's not and shouldn't be on them at all to manage.
The onus of end of life care should not be on one's children. Period. They get to show up and grieve, and that's it.
I'm only 41, and my life or death decisions are mine alone and already planned through my will and advanced directives. My estate is already managed. My care is already planned through accounts for in home or facility care. My death and funeral desires are already accounted for and in writing. Etc etc.
Parents need to come to the realization that, in a perfect world, we will die before our children. No getting around it. And then not fear the planning of our own care and deaths, leaving those burdens on our kids.
If (general) you are a parent and you haven't yet...get to a lawyer and get a will drawn up, and get to a doctor to manage your advanced directives.