Since we aren't currently drafting anyone I don't think it is a concern. I would think, in time of war, although women are registered we would certainly take into account parental status. I can't see anyone advocating a nation of foster kids simply to include mothers on the front lines.
As the wife of a former airborne/ranger, I can testify that is what they always say (blacks, homosexuals, women). It never proves to be true. If the military lowers the standards to qualify women, that is their own mistake and PC-ness. Stick to your standards and let the results speak for themselves.
A fair way would be not to lower standards, but check to insure that standards in place have a direct correlation to successful and effective job performance. While their may be fewer women that can meet the physical qualifications for being a firefighter, there are always some that can. We must avoid blanket prohibitions against people, assuming that they are automatically ineligible because of gender or anything else not relevant to job performance.
Women in the military fill so many vital roles in today's fighting force, can't see why they shouldn't register for the draft. Our volunteer armed services have been successful for more than 40 years. Can't imagine going back to forced service.