If we take bioidentical hormones either by injection or transdermally (to avoid first pass effects in the liver), and keep our hormone levels within the range found in normal, healthy women/men, it seems reasonable to expect that our life expectancy (and our health overall) shouldn't be very different from that of natal women/men. The biggest problem is finding a doctor who understands that and works with us to achieve it; most of them don't seem to have the first clue.