All they've done so far was confirm that there would be a cash shop in one of their interviews- I can't for the life of me remember which one to source, but I'll throw it up here in an edit if I find it again. However, I'm pretty sure they specified that it would contain only cosmetic items and the like - [the following is speculation] probably things like horse skins, armor, character slots, bag space, etc. So it won't be pay to win like f2p games are.
As for the ring partners, as I understood it you paid for those +xp rings with in game gold... they never specified one way or another, though, that's just the impression I got. I could be wrong.
The cash shop though, combined with the fact that TES fanbase is used to the one-time-payment of TES games with additional purchases for things like expansions/DLCs, and also the fact that TESO will be on consoles makes me think (hope?!) that it might be a B2P at $60 or so + nonessential cash shop game. With, of course, needing to pay for expansions that come out.
My only solid comparisons are GW2 and WoW, though. GW2, whether you like the game or not, continues to pour out new content pretty regularly. New storylines, areas, minigames, armor, even dungeons are churned out at a reliable rate. GW2's model is that B2P + cash shop, and appears to be doing alright.
WoW, on the other hand, puts out content less frequently (or it did the last time I played) and new content is far less noticeable most of the time. Even with a subscription of $15 a month I never felt like I was actually getting $15 worth of new content every month, which seems to be what a subscription model is supposed to do. Granted, this payment system works super well for them- it just hasn't been a sustainable system for most other P2P games. WoW is more or less a wildly successful fluke.
It's TES. Around, what, 12 million copies of Skyrim have been sold? That's a lot of fans. Combine that with a fair amount of MMO players who have never touched a TES game, and even if a couple million don't play, they'll probably break even pretty fast, and then make a nice profit. And a lot of those players will want numerous alts, so that's + plenty of $$ for that. Bag space too, don't forget. Pretty mount colors and extra customization, yes please, more $$ there.
Anyway, I'm hoping for the flat price of $60, and will gladly pay out the butt for character slots and bag space and pretty horses if it means no subscription. I have several friends who will only be able to play if there's no sub. :<