| The market has a lot more exposure due to WOW which is a good thing all around and should have created a larger player base that other companies can pull from. However, as Moorgard said, companies tend to screw up the execution of facets of their game and thusly can't get subscribers to migrate.
You also have the 'strike while the iron is hot' in these games and that is your launch window and the first few hours of play. By all accounts EQ2 is a much better game now than it was at release, yet it hasn't benefitted from the WOW exposure to any noticeable degree due to the fact all of its changes came years after its initial launch.
The degree of polish and fun that WOW provides makes the subscriber a much harder sell for other games even as it is bringing in new people to the genre. In some ways it is a double edged sword; WOW brings new folks to the table but it gives them a set of expectations for a game that very few publishers have been able to provide. | 