XI still has between 250-500K subscriptions as well (the latest mog marble sale figures put it around the 300K mark, but that number is actually growing as people return for the next expansion.) It's entirely possible that ARR can hit and sustain half a million subs for the year or so necessary to make money.
They'll also get a big initial cash infusion from the PS3ers, even as they give away hundreds of thousands of copies of the PC game to past subscribers. Unlike other console games, console MMOs have very little resale value initially (since the code can only be used once), so anyone who wants to play on PS3 will pretty much have to buy a copy that first year. (The resale value of console disks goes up once the price of the PC registration codes goes down, which is why people are still paying $30 for used copies of FFXI for Xbox 360 on eBay.)