It's been a long time in coming. The M9 is getting old & beat up. The grips are huge & the U.S. military STILL has two handguns; Sig M11 & Beretta M9. The U.S. wants modularity, something the P250 & P320 offer; one serialized trigger group that can be changed for grip size, gun size and even calibers if needed. The modularity of the P320 isn't just frames & slides, the trigger group & striker are also replaceable as a module. No part fitting, milling & time consumption. Fix & run. Kinda like the Styer AUG, everything is in modular groups.
Makes sense, how many fighter & helo crews want a full size 5" handgun? Most want the M11. So, they're issued the trigger group & they can now choose full or compact & grip size. There's plenty of male & female MP's that struggle with the M9 grip. A system like the P320/250 makes sense.