It looks like its starting. The Tau Hammerhead Gunship is no longer available on the GW website. I did not know that this model was being replaced, but now it looks like it is at least getting a rebox.
Here is the link for those curious. I did a quick look around and did not see any other models that were no longer available (codex either), although I do not think they can be ordered now.
Thanks to Christopher for pointing this out.