The rise in popularity of optics, such as the Trijicon RMR, has holster makers looking at ways of making scabbards for carrying them. Safariland has been working on new holsters for the military and for law enforcement.
At Media Day, Safariland had this drop leg holster on display that was made for an undisclosed military unit. As you can see from the bump out in front, the holster was clearly made for an optic equipped handgun. More versions of this style holster should be rolling out soon.