The Elder Scrolls Online Twitter has a new post that lets players know that the next update will feature the Imperial City, set to be released after the console launch in June and to be followed by Orsinium sometime after that.
@CaptainDumac We plan to release Imperial City after console launch, and Orsinium is slated for release after that.
— Elder Scrolls Online (@TESOnline) May 5, 2015
We'll keep you posted as details arrive.