7 millions+ people are not paying Blizzard already (me included) because the game they sell now it's not the one I subscribed years ago. It is not an MMO nowadays, you just hang around in your personal space, click to get in instances, click to get a selfie, click to buy some gold. I miss the community and the sense of exploration, and private servers, especially those on Vanilla or TBC, are the only ones giving me that feeling.
It's years the community ask Blizzard to give us Vanilla/TBC servers, and let us play the game we love. Most of us will pay an higher sub if required, so it's not being cheap.
Closing Nostalrius will not bring more people in retail, but the opposite. Most of the people I know are dropping their subscriptions BECAUSE of the action Blizzard has taken. Instead of solving the cause, they are sticking they head in the sands, telling us we don't know what we want, that they know better. Well, numbers don't lie, and the game is empty.
So yeah, good work Blizzard, you managed to kill the biggest game in history. And they could make a lot of money with a couple of legacy servers. Those have no costs, except for limited maintenance, and the game development has paid itself years ago. So it is virtually pure profit.