I personally see them becoming popular with private security concerns, as it prevents their weapons from being utilized with non-standard ammunition. It would require anyone that possesses one to have a special security permit, as well. It means they would be less common on the street, so would stand out more.
"See Mr. Joe and Jane Citizen? Those guys obviously had stolen hardware, nothing to do with us!" would be the line if someone were caught committing a crime with the weapon.
As for military? The military uses tried and tested technology (read, older). Maybe they will use it 60 years from now, but for right now the normal cased ammunition/weapon is king.
