There's still so many things we don't know about the human body.. This would be interesting if true, but they'd have to do some crazy things to allow people to live that long.
Restrict who can/how many people can benefit from it, possibly sterilize people or strictly control sex.. It's human nature to want something but not have to pay a price for it.
We don't know the limits of the human mind--even if we could keep the body alive, there's no telling when the mind would "become full" and you'd no longer be able to process new information, or perhaps the brain would forcibly discard other data and you wouldn't remember your childhood or various things that you learned.
It boils down to Earth. Earth can only support so many people, and there are no other habitable planets in the solar system. And don't say "We could terraform Mars," because that's just as much science fiction as this thread is.
