[Legbreaker]

It depends a lot on the nationality involved I would think.

Soviet style armies for example place very little authority with NCOs leaving most of the more technical and administrative tasks up to Officers (so I believe). Pushing NCOs up to fill these roles may not be a particularly good idea since they're likely to need almost as much training as a civilian trainee.

In many western militaries (speaking specifically about the British model here), NCOs are the backbone of the army - without them nothing can happen. It's relatively common even without a war going on for Sergeants and Warrant Officers to receive a direct commission (Corporals still need training). While not an everyday occurance, I've personally seen it happen on several occasions when either the officer pool got a bit low, or as a way to hold on to highly experienced and valuable SNCOs.

As Jester has pointed out, the number of enlisted soliders is also likely to reduce, thereby reducing the need for some many officers. However, historically, the proportional casualty rate for Officers and junior NCOs (the senior NCOs usually being employed in plattoon, Company and Battalion HQs rather than on the front line) has been higher than for enlisted. This is most commonly due to the risks a commander must take to remain in control of the situation - they have to put their heads up out of cover to see what's going on.