It seems that the relaunch of Final Fantasy XIV: A Realm Reborn is such a success that Square Enix’s servers actually can’t handle all of the users trying to either buy the game or log on.
To compensate for this overload, Square Enix is temporarily stopping the digital sales of the game. You can still get the game, you’ll just have to find a retailer that carries it.
From what we’re hearing and seeing the reboot of Final Fantasy XIV seems to really be a success, especially now that we’re seeing their servers being overloaded.