According to Michael Zenke from Massively, Age of Conan has sold 400,000 copies, out of 700,000 boxes they put on the shelves. Not bad for the first week. And, kudos to Funcom, the release launch went a lot smoother than the beta or early access. The reception of AoC in the blogosphere was a mixed. Keen and Graev already cancelled their accounts again. Tipa from West Karana sees AoC challenging WoW. The Ancient Gaming Noob correctly points out that "MMOs are a long haul proposition" and reserves judgement until having played it more. And the Common Sense Gamer thinks that WoW won't even notice AoC is out.
So here is what I think. I don't have proof, only anecdotal evidence, so preface every phrase here with "In my humble opinion": I think that World of Warcraft suffers from a cycle of peaks and troughs in subscription numbers. This is largely self-inflicted, numbers peak after big content patches and expansions, and fall in long periods of no new content added. Other factors, like summer holidays, also play a role. I do believe that WoW is heading for a major trough of subscription numbers in the western world. Remember that of the 10.7 million WoW players about 6 million are Chinese, who are on a different cycle, and who pay much less. There are less than 5 million players in the US and Europe, and the number will be falling over the summer, because the Burning Crusade is getting long in the tooth, and not everyone likes to spend his summer holidays in front of a computer.
Age of Conan will reach between half a million and one million subscribers this year. Most of which will be ex-WoW players. A good number of them will have stopped playing WoW anyway, with or without AoC, but a couple of hundred thousand will be pushed over the edge and quit WoW for the prospect of a new game. And Blizzard will notice that, because all of these are the well-paying US/Euro kind of subscribers. Age of Conan will not "kill" World of Warcraft, but it will dent it a bit.
Summer will end, christmas will approach, and now everything is possible. WoW could bring out Wrath of the Lich King in November, and it's subscription numbers would peak again. And personally I don't see Age of Conan having much staying power, not in a game where the first people reached the level cap in the first week already. Wrath of the Lich King will make a much larger dent into Age of Conan's subscription numbers than AoC does into WoW's now. But another possibility is that Blizzard misses a 2008 release date for WotLK. And it is also quite possible that Warhammer Online makes that date, and comes out for christmas. And then Blizzard would really start feeling the pain. I do believe that WAR has an even bigger potential of getting subscribers away from WoW than AoC has. If WAR comes out for christmas and WotLK doesn't, they could easily sell a million copies this year. Again, these are all Americans and Europeans, and if WAR beats WotLK to a christmas release, WoW numbers could suffer an even deeper trough.
None of this will "kill" World of Warcraft. But we are talking numbers here that are big enough to show up in a companies annual report of revenue and profits. If Wrath of the Lich King doesn't come out by the end of this year, the 2008 profits from WoW will be significantly lower than those of 2007, and investors and people at Vivendi will notice. Blizzard would bounce back to a dominating position when they bring out Wrath of the Lich King, but then what? If the third expansion is still another 2 years away, the overall trend of WoW subscription numbers could well go into permanent decline. One day WoW won't be the biggest kid on the block any more, not because of one WoW killer, but because of a death by a thousand cuts. The best Blizzard can hope for is that the new champion will be their next generation MMORPG, but that is not a given.