Take it from someone even older (I turned 80 in Feb) the aches and pains don't go away but if you keep active as best you can that's the best thing to do. All of my cats are gone now and Darick, my one remaining dog, won't allow me to get a cat. He is nearly 9 yrs old and needs walking and some ball/rope throwing every day so I have to give him lots of attention.
It might be a good idea for you to foster, or even adopt, an older dog. I understand your worry that a dog may outlive you as I have the same fears about Mr D, but I have arrangements in place with his breeder should the worst happen. Good luck