They are stopping production for two reasons
#1 a Colt AR starts at about $1200,,and you can buy basically the same weapon made by Smith&Wesson for $599 anywhere,,,and other brands as cheap as $399. Colt can’t compete in the civilian market.
#2 is that the military is switching to a 6.5mm weapon and Colt is developing the new platform for them. They will have a leg up on all of the other manufacturers for a Couple of years when the Army switches and every redneck in Murica will just have to have the new bigger assault rifle