Dark Heresy, Rogue Trader, Deathwatch and Black Crusade are enough. Black Crusade should have been the end of the 40K line and the existing products expanded and built on. All things considered, four RPG games in the same setting already pushes the boundary. Five? I'm not buying. The idea that throwing out content and sooner or later something will be a success is a real turn off. If anything, build what's already out and then learn the lessons of this set of mechanics and let's move on to 40K second edition - an edition that hopefully means the release of one core book, the unification of the disparate Psi powers and releases additional material for that one book. In short, there's no need for what's happening, and I personally am rather angry with the release of another rulebook.
I don't want a flame war with anyone on here, this is my own personal sentiment. There are better ways of doing things, especially when the books cost so much - enough already.