It is rather solid that we will not be seeing a Chaos Marine Dex for quite some time, next year. I saw this today when I was on Bolter and Chainsword, and figured it was talking about Chaos Daemons.
This got me thinking, that quite possibly we could see a decent sized update in the next campaign book or 2, like we saw for the Tau. So with the Curse of the Wulfen coming, and the Wolves facing off against Daemons... Perhaps there is a larger update right around the corner than we are thinking for both Chaos and Space Wolves. New models for both armies?
Here is the post I was reading. Note that I am speculating based off of the post below and what we have learned recently.
via SlaveToDarknesss on Bolter and Chainsword
Popped into GW today, manager had spoken to head office regarding the lack of Chaos dex's, they said they wont be sending any more to the store. Unsure if this is just to my local or all GW's, may be something or nothing but I thought I would pass on said info. *shrugs*
Make of it what you will.