When I was a kid, I got a kitten named Natasha. She stayed with my family when I moved away from home, but she lived to be 17.
When I was in college, I got a kitten named Carolina. She had a kitten named Casey who lived to be 15. When Casey died, I got my current girl cat. Shortly before Carolina died at 17, I got my current boy cat.
Girl cat is now 15 and boy cat is 14. Last winter, boy cat was diagnosed with a heart condition and my vet said the average house cat only lives to be 14. So I thought, chances are I'll only have them for a couple more years.
I figured at my age - 50 - I should be able to outlive another set of cats, another 15 years at least after girl and boy cat are gone.
But just now, I was lying on the floor and girl cat came over for a snuggle. And I thought, I wonder if I'll outlive you. Maybe my current cats will be my last ones.