It's a problem of divided playerbase, the organization and balance of the two compared to each other would be a nightmare. Make them two totally separate experiences and you've effectively cut your number of players for either game in half. Numbers like 1 million players sounds nice as a total, but it's critical to make sure these 1 million players are organized in decently populated servers to make it enjoyable. Make them interact with each other and you're struggling to maintain balance, particularly in a Warhammer game which would undoubtably be player versus player heavy. Of course, the cynical side would say that it's all pointless worrying about a balance of hardcore and casual players. What THQ is actually saying is that there's far more money in casual players and they're going to sell to this market more before they lose any more money.