When I was first diagnosed with breast cancer, I joined a support group at the hospital for newly diagnosed women. It was our introductory support group and we met weekly for seven or eight weeks covering different topics of life with breast cancer. Of that original group, there are five of us who still get together for coffee periodically. One of the members of the group was actually on her second breast cancer diagnosis. Then she had a recurrence a couple of years ago. Then we found out she died in mid-October. We didn't know. We were appalled. We never got to say good bye. We would communicate primarily by email. She used her work email address. She retired finally this summer. We think her husband didn't know how to get hold of us.
I spoke to another member of the group about this. She said she immediately turned to her husband and said 'don't forget to tell my friends if anything happens to me'. He wanted a list of who to contact.
We used to joke about my grandmother's 'in-case-of-death' envelope. She would write notes and put them in the envelope of things she wanted done upon her death - who to notify, her services, where things were, etc. If you do this for 20 years, you need to update it periodically. But when she did finally die at 96, we knew what she wanted.
I'm not planning on going anywhere soon but I will make a list too.