Producer PA. Works' founder/president Kenji Horikawa comments on possibility
Anime about making anime Shirobako engendered plenty of fan enthusiasm, not to mention sales. And its creators are evidently fond of the work. There's also ideas for more of it. Producer PA. Works' founder/president Kenji Horikawa has said that they thought up a year's worth of material. Unfortunately, it doesn't look like it's a good idea to peg your hopes on a second Shirobako any time soon, if ever.
In an interview in Animestyle 006, Horikawa downplayed the chances of a second season or movie, saying that director Tsutomu Mizushima has so much on his plate that his schedule is booked out for the next couple of years. It would be unfeasible to ask him to even try to fit in another OVA.
Elsewhere, recently revealed cover art from Ponkan8, original character designer on Shirobako (and My Teen Romantic Comedy SNAFU) - July July 29th with episodes 19-21, The Third Girls Aerial Squad and chance to buy tickets to a September live-event