While average lifespans are an interesting topic, they bear no relationship to real life. YOUR lifespan will be determined by (1) genetics, (2) extraordinary events (e.g., an auto accident, deadly disease, or getting shot), and (3) how well you take care of yourself. If the average lifespan for people born in your year is fifty or a hundred, who cares? It makes no difference to you. Statistically, having been born in 1949, I am most likely dead.
But I believe that I am an example of (3) above. I was diagnosed with a serious heart issue at 23, but I took it seriously and am now a healthy 76. I could die on my bike tomorrow and still beat the odds, unlike my mother and half her family who died between 35-55.
As for the generations following us Boomers, their prospects should be significantly better, mainly due to advances in pharmacology. But you still have to consider #3 above.