Sigma has just announced the leaked 16mm f/1.4 DC DN C lens for Sony E-mount and Micro Four Thirds mount. This is just a development announcement, price and release date is not available yet.
You can take a look at sample images of Sigma 16mm f/1.4 DC DN C Lens mounted on Sony a7RII.
Sigma also released a new lens roadmap for Sony E-mount and Micro Four Third mount mirrorless cameras, next lens will be Sigma 50mm f/1.4 DC DN Contemporary lens, available for Sony E-mount and Micro Four Thirds mount.