User blog comment:JAlbor/E3 2013: Answers from Elder Scrolls: Online/@comment-24489208-20130612234422

It says that it is predicted that ESO will be subscription based but since it is coming out on consoles as well, I doubt this since players of both PS4s and XBones need to pay for online features anyway and subscription models in this past fail on consoles substantially. For this reason I believe it to be single payment. Perhaps PC players will have to pay a subscription but console players will not.