http://www.escapistmagazine.com/news/view/127140-Elder-Scrolls-Online-Has-Five-Years-of-Content-Planned
They might have a few ideas mapped out for the future.
Explaining the latter point, Firor said: "The other reason is we really want a steady forecastable revenue stream so we can do constant updates. We're working on post-launch content right now, and we want to make sure we're covering all of the new content, which will hopefully be released every month or six weeks, for as long as people want to play the game.
"When I talk about new content, I mean, we're launching with the Mages Guild and the Fighters Guild questlines, but we're going to launch the Thieves Guild and the Dark Brotherhood at some point as part of the regular updates. And those are 15 hours of content a piece. We're talking major new stuff, which is going to be coming out constantly. And the way to do that the best for us is with a subscription."
Pete Hines' interview.
http://www.computerandvideogames.com/450862/interviews/interview-bethesdas-pete-hines-on-the-legacy-of-wolfenstein-and-the-eso-subscription-model/
I believe they have plans. Whether they can keep to their plans is the question.
With each of the faction questlines running around 200 hours *each* for $60.00 for the base game without pvp, I don't think they are exactly overcharging. There are a lot of games that give much less content and cost just as much. If they can add the content updates they apparently want to, I don't mind the sub. Pay $15.00 for content I want/am interested in, or wait and buy a $60 game that lasts for less than 20 hours that I might not be that interested in.....the $15 is cheaper, really. There are, as far as anyone knows at this point, no contracts written in blood and bound with the player's immortal soul that you have to stay subbed for eternity, so as long as you can quit if you want, there shouldn't be too many problems.