We will definatley put you in our prayers. My biggest loss in life was my dad at 16 years old. I understand your concerns. He will never get enough of you, nor will you ever get too much of him.
Many on here may not know it, but for several years since 2005 I would be in the ER with rythem problems ,a fib -bradycardia (at least a couple times a month) and a couple heart attacks. I still get around, a bit slow but worse things could happen. Thankfully the Docs are still finding more & more reasons for my problems,and I have less & less episodes.
Your dad has a good chance to continue in a long happy life,with his loved ones. Love him ,help him don't baby him unless he asks for it. (OK baby him a little wheather he likes it or not)he will feel the love.
Most of all Thank God you have him in your life.