I tend not to keep long friendships & so I just drift in & out of knowing people. So I'd not have any wish to say goodbye, I'd just disappear same as usual.
It wouldn't usually cross my mind that anyone might wonder where I'd gone. Obligation & responsibility to let people know if I'd croaked? I wouldn't have thought so.
I hope that doesn't seem mean & nasty, its just an honest answer to the question. I'm just an 'out of sight out of mind' sort of person in both directions.

Kris