The reference is inside of an Apple TV framework related to the device’s AirPlay functionality. The mention of the next Apple TV is the highlighted “AppleTV4,1.” The current Apple TV is “AppleTV3,2″ while “3,1″ is the 1080P model introduced in March 2012, and 2,1 is the first iOS model introduced in September 2010.
A jump from 3,2 to 4,1 would suggest a significant update to the internals of the device.
Currently, it's expected that Apple will release the device around March when an iOS update is also expected to drop.