KyoAni speculation:
-Before Tamako Market, Ishidate had directed the finale for the three KyoAni TV anime in a row (shared in Hyouka's case and solo in the other two).
-Similarly, he'd directed multiple episodes in every new KyoAni TV anime since 2006 but just recently broke the tradition by only supervising one episode in both Chuu2Koi and Tamako Market (the last episode for the former, episode 7 along with Ishihara in the latter). Considering his involvement with the studio doesn't seem to have decreased at all, it's easy to guess he's busy with something.
-Among the KyoAni members that haven't had as much spotlight as expected there's also Chise Kamoi, who for the first time in a couple years hasn't been picked as the animation director of a single episode in one of their shows.
-In a mass update of their CM staff list, KyoAni revealed that the Kyoukai no Kanata promo (http://www.youtube.com/watch?v=aK1fLm4VrDA) had Ishidate as the director/storyboarder and Chise Kamoi as the character designer. Considering Chuu2Koi's success and the length of KyoAni's production schedule, it could very well be that the project's in early stages so they haven't been able to do much in other series. Late 2013/early 2014 Kyoukai no Kanata adaptation? Sounds likely to me.