While I agree that the subscription cost is the most likely payment model at launch, I won't completely rule out the other payment models. There are numerous reasons why ZOS might pursue a buy-to-play or "freemium" (B2P/F2P with the option of a monthly subscription). A few of the biggest reasons include:
- Pay to play games are a very small minority of the MMO market (currently only 15 MMOs running right now have mandatory subscription costs).
- Free to play/buy to play games have generally improved in the quality of content provided, creating market pressure for other games to follow suit (in other words, a studio has to deliver a very impressive game to get and retain an adequate number of subscriptions).
- Multiple MMOs that launched under subscription plans and later converted to F2P/freemium models have actually become more profitable than when they were subscription only. Some call this the "silver medal of MMOs", but if a studio thinks they'll make more money by following a non-subscription model, they're going to follow that model.
At the very least, it looks like ZOS is setting up the framework to convert to freemium if it becomes necessary--The presence of a cash shop (stocking vanity items) is already confirmed. If you take the language used in some interviews literally, they also talk about additional content as DLCs.
Final Fantasy 11 has a subscription, is (or at least was) available on Xbox 360, and back in 2006 was in the top ten it ranked (number 6) most played games on Live. Of course, that's a game that's over ten years old and seven years past its prime, but you just wanted a subscription based game that did well on the 360, and I'd say that FF11 qualifies.
Subscription-based games on consoles are very rare, I'm not denying that. But you can't refute that no matter what, if you're required to pay a fee for your PSN/Live membership in order to play games online, you'll be paying that fee no matter what payment model ESO uses.