Cats can live 20 years or more. Do you have family or friends who would take in your cat if you became unable to look after him? My neighbour took in a 6 month old pup when he was 77. His son will take the dog if something happens to him. LOL, he re-married this summer, at age 78; she's 78 too. So he took on a wife as well. I'm pretty sure his son is off the hook for his wife.
Personally I think taking in a rescue cat or kitten at your age, regardless of what happens down the road, is giving a needy animal a chance it might not otherwise get, right now.