In fact the whole stickmonkeys release schedule blows out a lot on the current line of rumors, not only from Straightsilver and Ghost21, but from a whole host of other sources. Of course, GW often changes their minds and delays things. It could very well be that Chaos Legions was just now decided to be pushed back, and Stickmonkey just has the quickest handle on the latest information. We shall see.
Please remember that there are quite a few rumors in here, take with salt.
Hmmm, well I have the Legions Dex down as a lot earlier than 2013 (earlier than many may think) but of course nobody really knows so 2013 is as good a guess as 2012, and I get the impression they do really want to make a big deal out of them which would explain the delay.
Tau in Q1 is a very big possibility. I had been told that Tau have had new models ready since June 2011 by somebody who has (allegedly) seen them. I was under the impression they would get a wave release with a WD update but this seems to have been canned in favour of a Codex. From June to Q1 is enough time to develop a Dex so that's certainly possible.
In terms of Marines, all the new Codexes (with the exception of Space Wolves) have had models which use the new flying stand ('Nids will get the Harpy at some point).
There is definitely a push towards large models and when asked why only Grey Knights and Blood Angels get Storm Ravens at Games Day it was inferred that they are the only Chapter that use them, but that other Chapters use their own variation of flyer.
So it's possible there will be a new model which will feature in both Black Templars and Vanilla akin to a Storm Raven and will appear in both Dexes.
This means that the Vanilla Dex and BTs could be released close together, in a similar way that Blood Angels and Grey Knights were.
And GW almost always releases a new Marine Dex with a new edition, so with Edition 6 arriving in Q2/Q3 next year it is more than likely.
it's not unheard of for GW to have models ready for months / years and still sit on them, so Tau could be Q1 or not even next year.
I had heard Chaos Legions would be next year, and earlier than previously rumoured, but then again that same source said Tau would be 2011 so that's questionable.
It may just be that Legions ended up being bigger than they expected and they want to do a "Dark Eldar" on it.
Plus it's almost definitely going to be Chaos + something else in the 6th Edition starter set so they may want to wait until sales of that have kicked in, which would be Q1 2013.
I hope not though.
Well it has been stated that 2011 was a Warhammer year and 2012 will be a 40K one.
I wouldn't be surprised if Necrons follow the same model Dark Eldar set, so a wave in January followed by a 2.5 wave in March/April.
There was also a second 40K release in 2011 (Grey Knights) whilst DE were being finished off.
Therefore I would expect a Q1 2012 40K release.
As to what this will be is anybody's guess.
Sisters are still a long way off.
GW were reluctant to rerelease DE (it was pretty much Jes Goodwin that championed them) yet they proved to sell well despite a long break between codices.
I suspect GW feel the same way about Sisters, rather waiting to do them properly rather than rush them out.
Jes did say in October 2011 that they were on hold for the time being. That doesn't mean they aren't being worked on now, but I think there will be other releases long before them.
As to the rest of the year, we have edition 6 coming out in June/July, probably with a new starter set in Q4 2012.
2013 will be the year of The Hobbit / LOTR so I suspect we will get lots of 40K stuff crammed into 2012, especially as it's also the 25th anniversary of Rogue Trader.
However 2013 isn't really that far for Chaos Legions.
Let's be honest, this isn't GW failing, they haven't officially announced anything, they will release stuff when they are ready, not before.
Do I think it will be 2012 though? Yes I do. There is almost no doubt Chaos will feature in some way in the new starter set (of course I'll look silly if they don't...) which is out Q3 2012 so it makes sense that the Chaos Legions Codex will be the last one before the end of that year. Then a wave 2 release January 2013.
However I have heard rumours it will be before that, but as that contradicts absolutely everybody else I won't go into that.