It's actually a good idea to have two cats, they socialize with each other. When I was going to let Hobo be my single cat it was because I was thinking about the fact I'm not getting any younger and a cat is about a 20 year commitment.
Then I realized, she was just over a year old, another young cat was not going to change the commitment by much.
I honestly dunno how I feel about this. It kinda makes me feel a certain way.
Is it ok to have a cat that might suffer simply because they outlive me?
Well it is likely my niece would take them in if that happened and they would have a good home but it's still something to think about. I guess because I often consider them to be like kids who never grow up, I also give thought to what could happen if I wasn't around to care for them.
Hobo and Tramp will be fine. I'm sure you'll enjoy them for a longer time.