She is a little older than her cohort life expectancy at birth (which was 78 in the USA in 1945):
https://www.ssa.gov/oact/TR/2011/lr5a4.html
Assessed in 2010 at the age of 65 she might be expected to live to 85. That seems quite likely.
If anything you would have to say it leans towards extending her life because she will not be eating less like elderly people do, she is likely to have excellent venous health, her reaction times must be good, and prosaically she's so physically fit that just that much more likely not to be derailed by a fall. Living at her age starts to be a question of intent but there are loads of really small things that can trigger decline; she is robust against many of them.
What a remarkable woman.