Relic doe. They have a history of making good games.
Additionally, there are screencaps of gameplay, but only a few places have seen it. It's been reported it looks good so far, but as far as the product is concerned, I think they're still a year away from a solid demo. If you look at the YouTube channel, the oldest video there is a year old, which means, to me, that they've at least been working on DOW3 that long.
Why?
They had the mind to even make the Dawn of War channel on YouTube. No reason to showcase the videos they were at all, as these games are years old. Let other sources have them at this point. But they're working on a sequel, so they want to have all of this old shit ready to show off, and a place to put the new shit right next to it. They were preparing... for war advertising.