In addition to the rumored Zeiss Distagon 25mm f/2.0 lens, there could be a second new Zeiss Distagon 16mm f/2.8 lens:
"Oh, by the way, for those who's interested in astrophotography and ultra-wide angle, Zeiss will be releasing a 15mm/2.8 soon, and it will be available in both ZE and ZF mount, for more details, please wait for Zeiss official announcement."
The original source also confirmed the 25mm f/2 lens:
"Finally ... Zeiss ZE 25/2, while the previous 25/2.8's advantages are color rendition and macro capability on film, the newer version is better in image resolution and uniformity)".
Via ZeissRumors