The Army only ever downgrades it's ordinance for two reasons. Lack of a serious threat, and costs of the Guns and more properly the Ammo, and this always comes back to Politics and their perceived ideas on what is needed Right Now. The concept of "tomorrow" is totally foreign to them, that's why every time there has been a major conflict, our Military's Ordinance Stockpile has always been behind the curve.
We haven't had a serious threat to our Military since Vietnam. Then politics got involved and gave a contract to Beretta for a 9MM pistol to appease NATO. The .45 ACP was gone as was the most effective side arm in History which served for 75+ years. The Beretta was not better, it was cheaper, as was the ammo. Simple as that.
The unproven Sig 320 was priced at $207,,, the proven Glock 17/19 was priced at $270 and so Sig got the contract. They both were 9MM cuz it is the Cheapest Centerfire Pistol Ammo there is.
When the numbers come out on how many rounds were fired versus enemy kills we will finally see the difference between the 9MM .40 S&W and .45 ACP and very predictably the .45 will have the least rounds fired per kill, with the .40 second, and the 9MM having the most rounds fired per kill.
That alone makes this move more dangerous for our soldiers. And it's all about the "Benjamins!" And "Acceptable Losses" and as long as you can stay inside those "acceptable losses" for less $,,,, then that's what they'll do.... Everytime!
my .02
Randy