Yes, you're right, of course! I had my head turned around also when I first posted. Larger dogs have shorter life spans typically. My sister and brother-in-law have a Great Dane and I know one of their biggest concerns before getting it was the short life span. It's hard to let a pet go at any age but knowing that you may only have 8-10 years with your dog is a little sad. I stand corrected!
There is never any guarantee that your dog will be healthy and live a long life. The best advice you've gotten here is to love your baby and do all you can to make sure he/she is well taken care of.