Although the move to the 5.56mm for many police departments and entry teams can certainly be understood, it does not mean it is a move for everyone… or even the best move for many. The debate over the move to patrol rifles from shotguns is similar. In fact, for many the move to a rifle caliber may not even be in the cards. This can be for political reasons, state laws, or simply the preference of a particular chief executive.
As the cost of rifle systems continues to rise it presents another set of issues for many police departments. There may come a point someday where most agencies simply cannot afford them or the ammunition to feed them. That means other alternatives are nice to have, and one of those is the sub-machine gun or similar weapon.
A shoulder-fired weapon in a pistol caliber is still a viable choice for many. There are a number of advantages to a pistol caliber entry weapon, sub-machine gun, or even a long barreled weapon in a pistol caliber. After attending every phase of training with a subgun I never felt “under-gunned” with the 9mm or .45 ACP. Like anything else in this world it has its limitations, but the ability to be lethal was not generally one of them. The typical lack of recoil makes them deadly accurate, especially on the move, and they are inexpensive to shoot as a general rule.