Sigma is rumored to announce a new 24-70mm f/2 OS HSM lens. The lens is expected to be released next year during the 2014 Photokina show in Germany. The new lens will be priced below the Canon's 24-70 f/2.8 ($2,299).
Update: here is a mockup of the Sigma 24-70mm f/2 OS HSM full frame lens by fotospekter.si:
