Nothing is safe from dataminers anymore, which is the lesson Bethesda Softworks are learning this week about new content coming to The Elder Scrolls Online. Word got out from a couple of different sites and threads that there seemed to be some space cleared out for some DLC content that wasn't in the game yet, and the immediate thought was that there was new DLC being setup for the game. With the word out to the public, the developers decided to just get it over with and planned an official stream to talk about the release.
— The Elder Scrolls Online (@TESOnline) January 6, 2019
What kind of content we'll actually get we won't know until January 15th, all we do know from the datamine is that the DLC will probably be called "Elsewyr" and it will happen in the land of the Khajiit, and that there seem to be plans for multiple content drops for 2019 in the mix. But what it all amounts to is unknown since we don't know the story yet.