Nice thread, I have been thinking about this topic very often lately. My guess is that we are, at most, 50 years away from being able to get the potential of living forever. I mean, I think in a couple of decades cloning and tissue engineering would be ready to do their jobs. The idea is, for example, that if your kidneys starts to fail, what you just have to do is go to the lab and then they will get your DNA sequence and then they will produce a new kidney for you. And it would work for all the organs, except for the brain. If you substitute your the brain, you are substituting YOU, so you die, lol. But I bet that in the near future there will be drugs that will perfectly heal the brain.
And lets not forget that scientific advances evolves in a exponential speed. Maybe in 50 years living forever would be even much more easier and simpler then what I just described in the first paragraph.