One of my daughters (6 daughters) is a National Guard Combat Medic. The nature of engagement today is very different from prior wars - anywhere in the theater is the "front lines" as the feckless terrorists use hidden roadside IEDs (often Iranian in origin) to indiscriminately kill soldiers, even medics. To some extent, women are already in combat.
As a veteran, I believe that the nature of combat does lend itself to co-ed units, compelled to employ makeshift sanitary facilities and sleeping accommodations. Other than once again using the military for social engineering, what purpose is served by this departure from military history?