Deadline notes that this particular news is surprising considering that Darabont had just been at Comic-Con promoting the series. "There is speculation that Darabont might be off the show completely but I hear talks are still ongoing about him possibly staying on in a some capacity. Darabont, who wrote and directed the pilot for AMC's zombie saga, hails from the feature world and I hear he never quite adjusted to the daily grind of producing a TV series. Last December, he considered forgoing a writing staff for Season 2 and assigning scripts to freelancers but ultimately went for the traditional writing staff model recommended by the network and tapped Glen Mazzara as an executive producer and his No. 2. It is unclear if The Shield alum Mazzara, who has showrunning experience, would now step in to run Walking Dead."
From what Deadline has ascertained, the behind the scenes shake-up will not impact production of the series. Season two is scheduled to make its debut on the 16th of October.