Sigma has already released two new high-end art series lenses in 2016, these are Sigma 12-24mm f/4 Art, 85mm f/1.4 Art lenses. According to recently rumors on CR, Sigma will announce all new Sigma 24-70mm f/2.8 DG OS HSM Art lens before CP+ Show in Japan in February.
There is already a patent of this lens last year. The shipping date of this new lens will be before Summer of 2017.
via: CR