In a recent interview with dpreview, Sigma's CEO Kazuto Yamaki confirmed that they have plans to make lenses for Sony FE mount - "we'd either make a F1.4, or something different" referring to the Sony 55mm f/1.8 lens:
A lens like Sony's Zeiss 55mm F1.8 for the FE mount is optically superb but quite small and light. If you were to design 'Art' lenses for that system, would you try to strike a different balance between quality and size, and try to make the lenses smaller?
Yes - that's also one of the segments we're interested in. Another motivation for us to make new lenses is to differentiate between other manufacturers. Sony already has a 55mm F1.8 which is nicely sized and reasonably priced, so why make another? But F1.4 compared to F1.8 is a huge difference, so we'd either make a F1.4, or something different.
Similar comment was given by the CEO in interview with Imaging-resource in November last year.
