Just a quick update in case you are not following PhotoRumors: Sigma is rumored to announce a new 14-24mm f/2.8 DG HSM Art lens (via Nokishita).
This will be a direct competitor to the popular Nikkor 14-24mm f/2.8G ED lens ($1,896.95). Maybe this news will push Nikon to release a new version of their 14-24mm lens just like they did with the 24-70mm and 70-200mm models and complete the “Holy Trinity”.
Update – additional info on the new Sigma lens: