What many in here forget is that Blizzard isn't as independent as they once were when the game started. When the mothership demands changes, the changes will be made... When Activision says, we go f2p now, then the game will be f2p.
To wait for such transition until the subs are totally declining to 4, 5 or 6 mio. is madness from a business view. At that point the reputation is so far negative that a switch to f2p wouldn't do much to save the day anymore.
And to the people who come in here to add their 2 cents.... STOP bringing up business calculations if you fail miserably at the basic math...
It is NOT 8.3 mio x $15.00.
WoW doesn't cost 15 bucks for everyone. The median figure for WoW is a lot lower per player.
Not only don't all NA players pay $15.00.... Most pay either $14 or just $13.
There's also a world outside NA which has millions of players that pay in different currencies, which again doesn't add up to everyone paying $15.00
And btw.. If you happen to pay your sub via credit card, Blizzard can kiss a certain amount of the sum you pay goodbye to the merchant bank etc.
CC transactions are not free. At least 3% of the monetary amount moved goes to financial institutes involved, and Blizzard pays that, not the customer. Some apparently have no clue about the mechanisms behind card payments.