Set up as a talkshow, the PC Gamer E3 2015 conference on PC gaming talked to Xbox head Phil Spencer about future plans for the Windows platform. Amid talk about the power of DirectX 12 and encouraging cross-platfrom games, Spencer casually states that Killer Instinct is coming to PC. 

Unfortunately, he did not elaborate with any details like what the release window will be or if it'll support DirectX 12, but the announcement by itself is exciting. We can guess that it will support cross-platform multiplayer with the Xbox One.