The teaser picture also has been updated to change from the Romulan symbol to a murky picture of warbirds among the stars when you mouse over it. The image caption reads, "Our shadow will dim the stars."
Will this be the reveal of a playable Romulan faction, as many have suggested? Or will it be the rise of a prominent adversary in the form of new mission content? Or could it be something as of yet unforseen? We'll just have to wait with the rest of you until all is revealed on the 21st.
[Thanks to everyone who sent this in!]