JASmith, wondering when you'd show up!
For those able to pull up the logistical stats for OIF and OEF and see how many rounds of 9mm were drawn, then subtract how many were fired in training (BZO), you will numerically demonstrate how frequent the sidearm is actually used across the entire forces deployed. Last time I looked at the data for the USMC, it was minimal. There are some specialty units that may frequently draw them, and train with them, but seldom fire them in kinetic engagement. For the majority of forces deployed, the sidearm has become an administrative nightmare on the accountability system. I know personally of many infantry battalions that had all sidearms returned to the armory in country, and reissued M4s as a matter of command policy to anyone typically rated a sidearm. Or shotguns, depending.
It is for that very reason (the logistical data) that many of the major suppliers are fielding civilian variant AR pistols (in the last couple years), as part of their product development for hopeful future military contract. Given that the terms "task oriented" or "mission specific" are peppered in practically all strategy development, a weapon that can be "task oriented" is attractive. The ability to convert an M16 to an M4 or an M21 DM version, using existing stockpile of parts, and minimal training for the armorers is very sexy to the brass. Throw a pistol length piston driven upper into that mix, and folks will be lining up outside the armory to draw one, and instead of a broom handle, they'll probably ask for a quick attach side folding stock and a single point sling. Add a reflex optic on as JASmith mentions, and we may see a revival in naming weapons.
Now take that task oriented platform and upgrade it all (pistol, mbr, dm) to the same 6mm caliber or higher, and you've got something that could attract the bean counters and shooters alike.