There are almost 18,000 agencies across the United States. The ammunition is more expensive than .45ACP and offers basically the same performance just in a smaller package. I give it 5 years---maximum.
23 Law Enforcement Agencies have bought Glock 45 GAP pistols, including North Carolina Sanford Police Department (Glock 37, Winchester 230-grain SXT; Georgia Fulton County SWAT Team (Glock 37, Winchester 230-grain RA45GT); Louisiana Office of State Parks purchased 90 G.A.P. Pistols; Piedmont Triad International Airport --- Autopistols 2006.
California, Huntington Park P.D. -- Issued Glock 37/Win. Ranger 230 and G22/Win. Ranger 165 only
Colorado, Denver Police Department -- Glock 37, 38, & 39
Georgia State Patrol
Kansas, Burden Police Department -- Glock 37
Michigan, Reed City Police Dept -- Glock 37
NC, Greenville Police Dept -- Glock 37
New York State Police (5,400 Glock 37's replacing their current Glock 17's)
Pennsylvania State Police
South Carolina Highway Patrol
Wyoming, Powell Police Department -- Glock 37