While this does not sound like a new codex, it could be some new models, or even a supplement update like we have seen recently. I thought this was worth sharing, although I don't really have much at the moment that confirms or negates this. There has been some very reliable rumors saying that we wont get a new codex until next year, however, Tau and Orks were out of left field, so I would not put it past Games Workshop to do some very quick updates.
Here is the rumor thread he is talking about below.
via anonymous sources on Faeit 212
CSM Rumor: Not sure what other info you have on this and my source has kinda dried up
on this for now, but I think your post about a future codex may be related to a release I heard about. Before things dried up it was confirmed to me there is a list of future releases, 3 to 4 months like the one that came out for Christmas, going out to GW stores and there are CSM releases on it.