This is the interview with Alessio that clears up what happened to the CSM Codex.
http://carpealea.blogspot.com/2011/0...-cavatore.html
Basically the design team were sticking to their mantra of "simple, simple, simple" and stripped out a lot of the stuff that was good about the previous Codex.
He admits that the current CSM Codex was steered more towards Renegade Chaos Space Marines.
In one of his Standard Bearer articles Jervis Johnson also talked about this. It was an article talking about the different design philosophies that had been employed in the past, and for once admitted when they had got things wrong.
He said that they knew immediately after they released Codex CSM that they had got it worng, and that it would remain as a Renegade CSM Codex, but they they had started work immediately on a new Legion Codex which would address these issues.
He did state in that article though that the current CSM Codex would remain, and that the Legion Codex being worked on be in addition to that.
I will need to go back through my WDs to find it as it was some time ago but I do remember the article quite well.
Bear im mind though that this was a couple of years ago so may now be outdated info, but all my sources are telling me that the current CSM Codex is staying (although it may get a WD update), and that the Legions Codex will be quite different.