For Photokina in September Sigma is rumored to announce the previously rumored 24mm f/1.4 Art lens and a new 14-24mm f/4 with OS. The 24mm lens will be priced at $1,099 and the 14-24mm will be $1,199. The 14-24mm will have an 82mm filter ring.
After the success of the 35mm f/1.4 and 50mm f/1.4 Art versions, a new 24mm lens would be the next logical step. There were also rumors for a new 85mm f/1.4 lens, but I have not heard anything on that model. Sigma may also announce the future development of a new 24-70mm f/2 lens.