"Some industry experts question whether the company will make significant inroads with military and police, which have moved away from submachine guns - in part because their pistol-caliber rounds can't pierce body armor. The gun's price tag - now expected to retail in the $1,200-to-$1,300 range - also could chill sales. " I have mixed opinions on the .223 for patrol LEO. Friendly fire on one extreme and the low recoil vs. a shotgun on the other. As for $$$ many small departments fork it over for AR type rifles. So cost would be a factor too, since shot guns are cheaper.
The .223 excells in two areas that a shotgun can't touch: armor penetration and range. Look at the North Hollywood BOA shootout: a shotgun (much less police pistols) were useless against perps in body armor armed with AKs. Useless. The cops were as helpless as babes until the SWAT guys arrived with .223s.
Plus, the .223 shoots flat and accurately out to at least 300 yards. Not that 300 yard shots are common in a patrol situation, but going back to the North Hollywood case, a single .223 in a patrol car could have ended the incident in the first minutes from a range of over 100 yards.