Sigma stated multiple times that they will not launch their own mirrorless system so I guess the patent you can see at Egami will be applied to expand their fixed lens DP camera series. There you can see the design and specs of a 30mm f/2.8, 30mm f/2.5, 28mm f/2.8, 24mm f/2.8, 50mm f/2.8 and a 55mm f/2.8 lens. All these will come with built-in stabilization system and inner focusing.
I still believe they should do a full interchangeable mirrorless system. But of course that’s just my modest opinion… :)