It's impossible to predict how the aging process is going to go for anyone. Or how that will impact judgment, overall mental acuity, and mood. Or openness to change and new ideas. Some people grow petrified in their thoughts, others keep learning and upgrading their understanding. I did not know Warren was 69 - she is certainly taking good care of herself. As an American woman, she would have, statistically speaking, about 6 years greater longevity than a male candidate. (In the UK, the advantage is about 5 years) Given the unique rigors of the presidency, I would feel some concern for a candidate who started their term of office at age 80 or later, no matter how competent and capable a statesman they might be.
Reagan, W.H. Harrison, Buchanan, George HW Bush, and Taylor were our oldest presidents. Trump now stands as the oldest president, being a few months older than Reagan, the previous recordholder, at inauguration. Not the most compelling lineup if you want to argue the virtues of older presidents. :-)