I'm sorry for the untimely loss of your friend, It's extremely sad when someone dies young, but as they say here in my country "death is truth," and everyonewilldie..
Regarding to the issue of passing on Bitcoin to our children or loved ones, this is essential, as you mentioned. It's not necessary for a person to be old enough to think about it; it should be considered at all times, because no one knows when their life will end.
Personally I'm still thinking about this. I'm trying to accumulate some Bitcoin for my children, but the problem is that life is becoming increasingly difficult and expenses are constantly increasing, making it hard for us to accumulate much. But we have to try.