Yes I often think about friends I had years ago- even back to my school days and wonder what's become of them. Since I've changed cities several times over the years I've lost track of most all of them. I've rediscovered a few- quite by accident on internet tech forums since people in the same profession tend to congregate in the same places but its never really the same- after exchanging a few emails about old times there doesn't seem to be anything else to talk about since we don't have much in common anymore.
And I think about how many people I knew who must be gone now- for years it seems I was always he young guy in the bunch so my colleagues were typically 10-20 years older- which means they are now all old retired guys in their 70s & 80s- if they are alive at all. I still find this hard to believe. I always think of people the way they were when I knew them- 30-some years ago. Its the same when I meet or see photos of distant relatives I haven't seen for many years. The kids I still think of as kids are now middle age adults with kids of their own. Life goes on.