SIG is aggressively pursuing a revamped lineup for 2015. As part of this, they have announced a new carbine: The SIG MCX.
SIG is being fairly tight-lipped about the carbine, but claims it is “the first to be designed from the start as a silenced, short-barreled rifle chambered in 300BLK” the truth of which depends on your definitions of most of the words in that clause. The enlarged upper receiver suggests the rifle utilizes an operating rod of some kind.
The new weapon will be offered as an SBR, pistol, and a 16″ barreled carbine. SIG has not yet announced a price.