lets be fair humanity will most likely be extinct long, long before the sun gets to that stage.
however if we aren't extinct by then (more than 3 billion years from now) then we, as in humanity will at the very least have colonized our solar system and would have at the technological level to surive anyway, either by moving to other solar systems (if we haden't by that point) or just by pure technology...
Also, why care about it? you will most likely not be alive 70 years from now, so why care about what happens 3 billion + years in the future?