What is the life expectancy for people born with cerebral palsy?

My brother is now 27 years old and was born with cerebral palsy. He is totally dependent on my parents for everything, but he walks ( not very balanced), but does not speak and has a mind of a 1 year old or less. He eats food but needs istance, needs to be bathed and all personal care. He has had many convulsion lately, and he is on a strong anticonvulsive med. The dr. just upgraded his dose, which makes him very drowsy and constipated, amongst other reactions. He has been very aggressive lately, trying to punch and kick, pinch people on the street, so my parents hardly take him anywhere anymore. (They don't live in the U.S., and they depend on public transportation). He does not go to therapy or school because he's ped the age in the country. He breaks things at home a lot. My parents are in their late 60's and are very tired of caring for him, but they love him and continue to do so. I suggested hiring a caregiver for a few hours a day, because then my parents could at least take a break. When my parents die, I will be his tutor, but I have no clue what is going to happen then. I am 35, married with a life of my own, working, going to college, and I live in the U.S. I am a U.S. citizen now. A friend told me not to worry so much because my brother should not live too long (I know, that wasn't too nice). But at the same time, I think of what life will be like caring for him on my own. Do you have experience with people with cerebral palsy and if so, could you give me some suggestions? Thank you!