Sigma is planning to release more prime art lenses in sometime 2014. One of these lenses will be Sigma 135mm f/2 DG OS Art lens. This lens has rumored for a long time, according to CR, this lens could be announced around Photokina 2014.
And there will be a surprise camera(Likely a new DSLR) announcement from Sigma, details for this new DSLR is not available yet.
via: CR