Here is a list of December releases, and the first thing that catches my eye is that both Escalation and Stronghold assault are listed as codex's. Time to pick up some Baneblades and fortifications.
Also of interest here are a new Desolation of Smaug book release, finecast releases for the hobbit, Codex Space Marine Ultima Edition, and Sigmar's Blood.
Also of note is that there are no Tyranids in this list, although we are still rumored to get a few model releases mid to late month for a codex release in January.
The above image is via an anonymous source from the Faeit 212 inbox.