Sigma has been very rapidly fleshing out its budget Contemporary line of lenses designed specifically for mirrorless, with the next one in the pipeline reportedly to be the 18-50mm f/2.8 DC DN.
This would be the tenth Contemporary, cheap-and-chearful mirrorless design, now comprising with its mates a rather complete set of understudy lenses to the Art lineup that has yet to be fully realized in mirrorless-first designs.
The lens is to come in Sony E mount as well as the collective L mount that Sigma employs, along with Panasonic and Leica. The Nokishita item linked above used odd language in talking about mounts. Sigma released the other nine Contemporary lenses in E and L mounts, but Nokishita indicated “it is unconfirmed whether other mounts will be released,” indicating its original source – a pre-publication review by a photographer given early access – may have talked of other mount systems.