Codex revision priority is set to two standards over at GW: Age of the current codex and popularity (read: cash can be made) of the army.
Of all the old 2nd generation codice only the Dark Eldar remain, whom are shelved for the time being. The Dark Eldar will NOT be phased out or reduced to a .pdf file army. GW is aware of the current state of the Dark Eldar. The army list itself is decent and robust, giving the army a good look and feel, the miniature line however is one of the most disappointing and hideous of whole of 40k.
The 3rd generation codice, for the most part recognized by being black books, is now slowly becoming the main focus of revision and internal additions. The Tau and Chaos marines have had their revision and soon the Imperial Guard will be next.
The 4th generation codice (A.K.A. the blue books) are for the most part the most current and final versions, with the exception of the current marine codex, which will be revised and re-released to include the new rules implemented with the Dark Angels (Combat Squads and basic marine load out). Current 4th edition codex books are Space Marines, Tyranids, Eldar, Black Templars, Dark Angels, Chaos Marines and the Orks.
As things stand right now, the following armies will get their own revised codex book in the next two to three years:
- Space Wolves
- Blood Angels
- Necrons
- Imperial Guard
- Dark Eldar
- The Inquisition
In the meantime GW is also producing supplements to make the game more fun and challenging, such as Cities of Death and Apocalypse. Main reasoning behind these releases is that not only is the game being made more fun, it can also facilitate and justify the release of new kits and miniatures. Cities of Death saw the release of models for almost all races, ranging from a completely new Imperial Guard regiment to a taste of new Chaos minis. Same with Apocalypse, which saw much needed revised minis for the Imperial Guard and extra minis Space Marines. We can expect the same of the upcoming "Planet Strike".
Forge World is also doing its part in making the hobby better. The last three Imperial Armour books not only contain rules and background for new units to use in 40k, but also special scenarios and army lists for more flavour and diversity.
All in all, 2008 is going to be a good year for the hobby.