The rub is going to come when you can only afford to buy GW2 or MoP. The competition's over initial box sales, not long-term commitment (at least, not on GW2's side.)
GW2 will probably cost about $60, MoP will probably cost about $40. Add in $15 for a month's sub time for returning players and you're at about the same price point.
Not everyone's going to have $120 to spend in a single month, or even a single season.
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It is impossible for a tear of sadness to land on a Warrior Beard. As soon as the tear lands on the Warrior Beard, it is now a happy tear.5:10 AM - Everything Nice: PizzaSHARK, you're my stand in! You're promoted to like.. Semi-bestfriend.
Problem is Blizzard will need to think about giving the retailers plenty time to prepare for their game release. I think a 9/11 or 9/18 date is more likely than any sooner. Yes GW2 is out before MoP this way but as much as they are both MMO's they are two completely different games. One is also free while the other has a sub. Not everyone will quit wow for it, and some people will play both (like myself). Sure its supposed to be a competitive market when it comes to MMO games but Blizzard still manages to wipe the floor year in and year out regardless of what comes along.
I can afford both boxes and several for poor IRL friends, which I have done in the past with many games. None of them have wanted a WoW Xpac since TBC... I bought LK and Cata for close family but it's not in the numbers for MoP. Not that I don't like pandas, farmville or pokemon, I actually love those additions, if they were in, "real WoW" not the hu$k that it is now.
Use this thread for release date speculation please: http://www.mmo-champion.com/threads/...d-release-date