No way in Hell, cod has a massive choke hold on the market, not even medal of honour has dented it, its a well known franchise with millions of fans, GW is relatively unknown to the masses,with fewer fans and its franchise is not best exploited by game, especially repetitive games which can't hold a persons interest
I dunno Call of Duty never changes, no one plays Call of Duty for it's single player, they play it for multiplayer. Call of Duty gets repetitive fast the only thing it has going for it is it's past. It's like the WoW of the FPS world and even WoW is ding now. What's needed is innervation, innervation that is properly support. Games that have gone up against WoW have never been properly back, mostly due to EA sports screwing them over.
Problem with FPSs facing Call of Duty is that they bring out a game add a bit of support then drop them and move on to something else. What does Call of Duty do? Keeps adding stuff until the next Call of Duty comes out which is soon because they have two developers on it.
Space Marine has loads of avenues it can explore, other races, other weapons, vehicles (which it has already started, kind of) bigger maps, bigger teams, move movement options such as crouching, prone etc. If it does all that it could rival Call of Duty in terms of gameplay if not popularity.