The big question of 'more races when???' still hasn't been answered by Relic Entertainment, but they've put out a new patch for Warhammer 40,000: Dawn of War III that does feature a few commonly requested changes - and a new map.
Announced just yesterday for a July 20th release, the upcoming community update introduced additional skins and customisations that should help larger units blend into the rest of your army's colours more easily.
4 new skins will be introduced alongside an edit of the Imperial Knight Paladin's mastery duds with 8 recoloured skins thrown in the aid the aforementioned need to have certain units match your wider forces with each of those eight available to tweak through the in-game army painter.
Ridding the concern of Gabriel Agelos leading Ultramarines into battle, the update will make Elite units more universally accepted across the board. You can refer to the third image to get an idea of what that means. Then, on top of certain UI changes, anyway, is the new Manufactorum map available across 2v2 and 3v3 scenarios that will make its debut next week.
As for the remaining skins; they're unlocked at certain points of the campaign. If you've already pushed through these, however, you'll receive them as you next log in. For the full low-down, read the community post over here.