This is has been brought up a few times, but is largely a non-sequitur. First, if WWIII broke out, I doubt women would be exempt from a draft (e.g. see Israel where service is mandatory for women). Second, this is comparing exceptional circumstances where there is, presumably, an existential threat to the state vs. a situation that can reasonably be expected to occur in a person's lifetime (pregnancy).

The draft is also a temporary measure. As with other wartime restrictions of civil liberties, like curfews or rationing, it would not be tolerated if continued outside the context of a war.

Why would you believe women wouldn’t be exempt from the draft?

Do you have a historical example of that in the roughly 300 year history of the US? Do you anticipate on recent Supreme Court rulings that they will expand the idea of equality and not reinforce traditional Christian gender roles?