User blog comment:G0LD3NF1RE/E3 Elder Scrolls Online Roundup/@comment-98.67.159.235-20130619073705/@comment-5469467-20130619234821

I just found a FAQ article on the Elder Scroll Online website, and it confirms that the game cannot be played offline.

http://help.elderscrollsonline.com/app/answers/detail/a_id/337/~/will-the-elder-scrolls-online-have-a-single-player,-offline-mode%3F