The primary increases in longevity over the past century have come from increasing survival into adulthood. If, instead of considering longevity at birth, you look at longevity at 35 (that is, how long you can expect to live if you've already made it to 35), the increases are a lot less dramatic. Furthermore, if you look at the records for "oldest living person", that number effectively hasn't moved in the last 200 years, and is stuck somewhere between 110 and 120, which should give you a pretty good idea of where the upper limit is.
Sure, with improvements in medicine, we can keep people productive into their 70s and 80s when they used to spend their last decade or so as invalids. The future of medicine looks like this: you're healthy and active into old age, then you hit the floor. No long suffering, no being bed ridden...but you still hit the floor at some point.
Entertaining the notion that we could live forever if only we spent enough on medical technology is one of the main reasons that we're in the situation we're in. You are not immortal. You will die.