At a preview event for UK journalists, the lead producer behind Ensemble Studio's real-time strategy take on the Halo universe suggested that downloadable content for the game could be in the works.
UK tech news site Electricpig spoke with Halo Wars producer Jason Pace at the preview event for the game, who indicated that while there are no definite plans yet, the studio is committed to supporting the franchise. While that isn't exactly a yes as far as DLC goes, he did mention that "additional downloadable content is something we’re looking in to."
Looking into is much better that breaking down in tears or punching the journalist in the face, so we're going to go ahead and put a check in the "Definitely Maybe" column.