Just a note about the testosterone levels in men and women typically, based on a couple minutes research just now:
normal women's testosterone is from 15 to 70 ng/dl, that is from .23 nmol/l to 1.07nmol/l!
With an IAAF limit of 5 nmol/l, that is nearly FIVE TIMES the high end of the normal range, which is itself almost five times the low normal. In fact, 5 nmol/l converts to 325 ng/dl, which is above the low normal range for men of 270. The high normal range for men is 1070, but the IAAF data did not indicate any advantage among men of higher testosterone than normal. Weight throwers were on the low end but perhaps that is from use of steroids causing lower testosterone.
So, this is actually quite a generous standard for the IAAF. The old IAAF standard was an absurdly high 10 nmol/l for women, which is equivalent to 650 ng/dl, which is very close to the male average of 679. Women typically show (Dutee Chand was reputed to have low androgen sensitivity) high sensitivity to even small doses of male hormone, so that their performances are much improved by greater testosterone levels. The upshot of all this is that women may well end up using artificial but covert means of raising their testosterone to 5 nmol/l, which would result in near world records for the most talented, I would imagine. Caster Semenya might just do what took place previously with apparent low levels prior to champs and poorer performances and then high enough levels at champs to be able to win if all out or at least medal.