the admittedly very small sampling I have to work with tells me that a guy or gal coming back from working in a forward area won't have much interest at all schlepping civilians around in an ambulance.
The military training won't get them NREMT certified either so they'll have to take a class first and when they find out how deplorable the wages are, well you can guess the rest I think.
If you're talking about the so called "tactical" side of EMS, I'd expect to see an influx of former military medic types trying to get involved in that over the more mundane civilian side.
In the broader medical arena, the overwhelming number of MD's and others will never need the sort of trauma experience that the military types have received and while it may sound good to have all of that experience in the ER, it won't make for better diagnosticians. There's only so much trauma surgery being performed on a regular basis in the civilian world.
If you're correct the net result simply be more of what's already happening in the job market. Too many EMTs, not enough decent paying jobs. Cue the anti labor union and the now almost mindless, "education is the answer" rants in 3, 2, 1...