Like many of you, I have parents. They are in reasonable mental and physical health now, but either they die by physical trauma or live long enough that that is no longer true. If they follow their parents and grandparents they will spend a long period where they are alive and possibly even enjoying it, but lack the mental capacity to manage their own affairs. No one wants this to happen, but it probably will.
If/when the decline happens, it will be useful for a trusted person with more mental capacity to have power of attorney over my parents. I have one sibling, and he spent high school saying “remember, I’ll choose your nursing home” every time our parents did something he didn’t like, so it’s probably me. Unfortunately, one of the hallmarks of incompetence in general is inability to recognize incompetence, and this only gets worse when you mix it with the belligerence of old age and dementia. I’m trying to imagine a more uncomfortable conversation than convincing the person who used to change my diapers that they’ve suffered an Algernon and should let me handle their finances, and there aren’t many.
As an attempted dodge, I asked my dad to write a letter to his future self that I could give him when I felt it necessary. The eventual product included both some tests he could run to see if now was power of attorney time (such as writing out multiple checks for the same bill), and stories of his parents and grandparents who had waited too long.
I don’t have any tips for how to have this conversation with your parents, because my dad is quite reasonable about these things and I punted the conversation with my mom to him. But it is something I recommend, early enough that your parents can consider it hypothetical.