A moody teaser image on dawnofwar.com pointing to some sort of announcement tomorrow at 3pm BST seems to suggest that finally we might get see Warhammer 40,000: Dawn of War 3. Relic Entertainment retweeted the link, suggesting they are involved.
Dawn of War 3 was in development previously, but was cancelled as then publisher THQ was forced to make some tough choices as they headed towards bankruptcy. Sega later picked up the studio, and have good relations with Games Workshop (as evident by Total War: Warhammer). Whether this announcement is truly Dawn of War 3 or something else, not quite as grand, is something we'll find out in under 24 hours.