I'm sure there's a fair chance I'm behind on the latest news from GW but in talking to a rep. today he told me that the Daemon Hunter's Codex is "out of print" and purposely hinted at the fact that they will probably reprint it.
Historically, when this happens it means a new Codex is on the way. The Tyranid stuff was out of print from a while before we saw them release the new book / models though, so who knows how long you'll all be waiting.
Anyhow, it's pretty safe to say that the Codex / models are "on the way".