World of Warcraft players would be taken away from the game for Warhammer Online. It is also inevitable that many of those players would return to WoW after trying out the new shinies. Yet, according to a recent interview with Blizzard COO Paul Sams at GamesIndustry.biz, more than half of the players that left WoW for WAR have since returned.
Sams states that this a typical trend for new MMO releases. "We've certainly had some of that happen, which is the same thing we experienced with Age of Conan and each time an MMO has come out we've seen some amount of reduction of use." He also gives his respect to Mythic and everything they're doing, stating that he thinks "Warhammer is best positioned to succeed out of the various products that have come out thus far since World of Warcraft has come out."