Just did some research looking to see if there's any trends in announcements for KyoAni works. Of the 7 series that were broadcast in April the following year, we had the following months of announcement: August, October, December (2008), December (2007), December, May, November. (
Haruhi (2006),
Lucky Star,
K-On!,
Haruhi (2009),
K-On!!,
Nichijou,
Hyouka). Obviously the
Haruhi (2009) announcement is a huge outlier, so I'm discarding it. That gives us a good range of fall dates for announcements. August and October have already come and gone, so obviously we didn't get any announcement then.
Hyouka was announced in late November and the two
K-ON! series were announced at the very very end of December (ironically the 30th for both).
If trends follow, we have a Kadokawa show coming up (which traditionally have been the spring shows (
Munto and
Full Metal Panic being the outliers)). The only Kadokawa show that was aired in April and was announced after October was
Hyouka; the others were announced prior to that (with
Haruhi (2009) being an exception due to making the movie). I highly doubt we'll see another
K-On! series since they've never done two TBS/Pony Canyon shows in a row, but if we reach December and there's not been an announcement, you could get your hopes up.
If you want to see the full breakdown (except for
Fumoffu, my researching skills suffered trying to find its news), you can look at
this spreadsheet. I just wanted to get a better view of when to expect an announcement.