Concerning the announced 40k MMO, I personally don't think that it could work in the 40k universe proper, unless some form of Battlefield-esque game were used.
The main problem? Most MMOs are individualistic by necessity. People log in at different times, have different goals, different play styles. However, the galaxy of 40k is not individualistic. Quite the opposite. A Guardsman is a cog in a machine. He has no choice. Same with Commissars, Lord Generals and even the mighty Space Marines and Inquisitors. Same with Tau, Eldar, even Chaos to some extent. None of them are the masters of their own destiny, they all follow orders. But that wouldn't make for a very fun MMO environment. So for a WoW-esque game set in the 40k universe to work, either fluff or game principles would have to be thrown out the window.
However. Not so for a game set in the more limited confines of the nightmare hive city of Necromunda.
The door slides open and you step tentatively out of the rusting freight elevator that brought you down to this hellhole.
A bleak scene greets you. Dim lighting everywhere. Ramshackle hovels, piles of garbage, large ratdogs darting by. Mean looking men and women lounging in doorways eye you up and down. You're suddenly glad you look as poor as you do. Maybe, just maybe, you'll last what passes for a night around here. The superstructure of the hive groans and creaks and a smattering of dust sprinkles down from the rafters two hundred feet above.
It doesn't matter who you are, where you came from, why you left, what you want. You are in the Underhive now, and that you means you are the lowest of the low, the uncleanest of the unclean, the poorest of the poor, the slovenliest of the sloven. There is quite literally nowhere to go but up. You have only the clothes on your back, an old stub pistol, a rusty knife and a couple of credits to your name. If you want to survive, it's going to take a lot more than that. Some guts, a low cunning and a lot of luck would be a good start.
No matter why you're here, you're here. There is opportunity and riches to be had if you're strong enough and smart enough to take it. But there's no time to lose. You can bet just about everyone here would like to see you dead before that happens, so you'd better get cracking.
Welcome to the Underhive, scum.
Seriously, this sounds like the perfect setting for a 40k MMO. You start out a newly arrived Underhiver in one of the shanty towns, and your career after that is up to you. Join a gang, make a solitary career as a gunman or outlaw, start as a ratskin, join the Merchant Guild, build an Underhive empire inch by blood soaked inch of girders, scavvie settlements, archeotech hoard and pipeways, but always always watch out for the Enforcers. Of all the groups out there, you don't want them noticing you....
I would be quite pleased if this is the approach taken by THQ and GW, but since Necromunda is one of the lesser taken paths of 40k, unfortunately it seems unlikely, perfect though it would be.
(@ moderators: I thought this a distinct enough subtopic of the other locked threat that it warranted a thread of its own. Not intended to be a restart of the thread earlier locked.)