I am no expert, but i know of no reasons why a woman with no history of heart or blood clot troubles shouldn't take HRT into "old age"
The medical profession has been going around in circles concerning the increased incidence of cancer, heart disease and blood clots and the conclusions are.........inconclusive:
Breast cancer.....might be a slight increase......MIGHT.
Uterine cancer......might be a slight increase......MIGHT
Breast cancer.......might be a reduction in cases.....MIGHT.
So there are MY thoughts, off the top of my head...so to speak.