I'm.. sceptical.. about the 40K MMO.
I get the horrible feeling its just gonna be WAR with a 40k skin.
The whole setting is incredibly dark, violent and hopeless. Every single race is xenophobic, violent and hateful, with each faction at the other's throats even within a race.
There are no good guys, and rather than being shades of grey it is more shades of gore covered black.
And that's without even getting into the Tyranids (not even individuals per se), Necrons (robot, emotionless, killing machines) and Chaos... which I don't believe can truly be represented in a game without a Mature rating.
As a setting it is also HUGE. 40k to me isn't about one world, at the very least it is about a system... more likely entire Sectors, not to mention the Warp space between.
To make a popular MMO this is all going to need to be toned down and sanitised. Unfortunately, nothing I've ever seen has been able to really make a toned down, sanitised, 40k without making it utterly unlike the proper thing.
Edit: In addition, the GW worlds have some major problems, that have been present for years, in encouraging a wider audience to pick it up. As a company, they almost solely direct their products and promotional materials to young males with disposable income. I've known many female gamers over the years who feel, very strongly, that GW is incapable of creating interesting female characters or including even that basic diversity within their races and factions.
One of the requirements GW has of video games companies is that they make their character models as similar as possible to the models. Look at WAR, and DoW, and you can almost see those characters as models.. if you took a screenshot you could even make people think it was a model if you set it up well enough. For fans, this is awesome.. for Jane Public it just makes her say "Why can't I make a female Chaos Warrior?"