http://www.pcinvasion.com/ex-world-o...izzard-vanilla
For those too lazy to read here are some interesting points said by Mark Kern who was one of the bigger names with World of Warcraft when he worked on it:
PCI: Do you think there will be enough support for vanilla servers from the community? There were 800K registered accounts on Nostalrius but only 150,000 active players.
Kern: Let’s put that in perspective. When we planned World of Warcraft, we only expected 1M sold and 500k active. And yet..and yet that was enough to bet the whole company on making WoW. It was the most expensive game Blizzard had ever made, and a huge risk. And yet, we would have been happy with 1M accounts back then. So I don’t understand this talk about 850k account not being worthwhile. That’s bunk. And you know what? With Blizzard officially behind legacy servers, you would see far more than 1M account re-activations. If a relatively unknown private server can reach 850k, then think what putting the Blizzard name behind it could do…far, far more.
PCI: Legacy servers have done well for the likes of Jagex but how much work would this actually be for Blizzard? Thinking about hardware, support, BattleNet compatibility etc. Would it even be possible now the game has moved on?
Kern: As for hardware, I’ll say this…what took hundreds of thousands of dollars worth of gear to host the original WoW servers can now be done for far less. Server hardware is so much better now, storage is so much faster now. We have VMs and cloud servers that can be spun up and down on demand. The Nostralrius servers only cost a few hundred dollars a month to run. Bandwidth is so much cheaper. The hardware is not the issue. Support is not the issue. They have more GMs now than we ever planned for or need for vanilla WoW. They have better tools than when we launched, that’s not a real issue.
I recommend giving the interview a good read. Though then again knowing who I'm talking to, they'll try to tell me their personal opinion means more than a guy who actually dealt with this and sees the validity.