It seems to be portrait prime day on Sigma is rumored to have green-lit the manufacturing development of its already-designed 200mm f/2. Such a beast would very likely be popular with low light sports and wildlife shooters, especially if it proved to take teleconverters well. Interestingly, the patent cited refers to this coming from the Sports line of lenses, rather than the Art line from which the excellent 135mm f/1.8 Art hails.