Here is what was said yesterday, followed by other information that has been floating around compiled by Kroothawk.
As with any set of rumors, please take with salt.
via Bols
So we all know this summer is Sisters of Battle in White Dwarf.
Next up is Necrons said to be in the November time slot (same as Dark Eldar last year)
Then Chaos Legions in the March 2012 time slot (same as the Grey Knights slot). This is said to not be a replacement for the current Chaos Space Marines book which may get some retconing and erratas to make it effectively the Chaos Renegade book come 6th Edition.
Yes I did mention 6th Edition - said to be hot on the heels of the Chaos Legion book, taking up next summer with the standard multi-month new edition release slot.
Compiled by Kroothawk about Chaos Legions
This was part of the 6th edition leak:
first real 6th edition codex: Codex Chaos Legions, really big release in three waves, doesn’t invalidate Codex Chaos Space Marines which gets extensive White Dwarf update as Codex Renegade Space Marines
ghost21 wrote:
urm (you do know theres going to be 2 new "armies" right to add to that list?)
As far as I know "Traitor Legions" and "Holy Inquisition", that is.
i can asure you the legion dex will have alot of varation
BramGaunt:
to clarify there is a traitor legion dex (...)
Some speculation by magnum12
Does fit with rumors about Renegades getting a WD codex to tide them over. Huron Black Heart would most likely be moved to the Renegades codex.
Things in favor of rumor being true:
1. IIRC some major GW employee said something way back about really wanting to do Chaos Legions to better represent the original traitor legions. Also might of said something about if it were to be done it would be shortly before 6th edition.
2. Whenever GW adds in a new faction, it is ALWAYS either the last or second to last codex/army book before a new edition comes out. Precedent: Ogre Kingdoms (WFB) and Chaos Daemons (40k)
Note: Does not seem to conflict with rumors about the Tau release since current intel said something about them being Q2 2012 IIRC. This could mean that Black Templar will be the token Space Marine first codex for 6th.
Speculation ahead: If my theory about fine casts and soon to be codicies is true, then we can rule out plastic Plague Marines and Raptors as well as a new Abbadon. Somehow I get the feeling this is going to be a BIG project so we may get lots of models for it. If this rumor is true, then IMO, the most likely units to get new plastic kits are Thousand Sons (hybrid IIRC), Noise Marines (hybrid IIRC), Dreadnaught (super ancient model), Havoks (hybrid), and a new unit. My money's on the Hell Blade as its both a new flyer and IIRC in the fluff, one of Abbadon's ideas.
Author is currently unknown. If this rumor is true, I'm going to predict it will be Phil Kelly.