Who knows the life expectancy of a German Shepherd?

I have this big German Shepherd at my house, and he's about six years old (turning this July). He has some arthritis and tons of allergies, so I figured that would set him back about 1 or 2 years, but now someone is telling me that the life expectancy is only 10-12 years! Is my nice dog just going to die in 2 years? I actually kind of weep when I just think about it...