Ok dudes, this discussion is all a bit silly.

As far as we know, there are no living forerunners. And since no forerunners have been met in Halo 2 (don't know about halo 3) there is NO WAY IN HELL, you are going to see Forerunners in Halo Wars, since it is set before the events of Halo 1,2,3.

And thinking about it logically, If either the UNSC or the Covenant had seen live forerunners during the 30-or-so years of war, you would have thought some form of canon would have mentioned it at some time huh?

So, no live forerunners in Halo Wars, at least not in Campaign/story mode. As for multiplayer? If we see them in Halo 3, it would be reasonable to assume that they may be available to play either with or against in the multiplayer mode of Halo Wars.

 As for forerunner artifacts and buildings, thats a given. We already saw a forerunner installation at 0:27 in the trailer  , and the covenant don't typically go planet-side unless there are forerunner buildings or artifacts there. They just glass the planet from orbit.

If this ain't forerunner, i don't know what the *** it is:

 It appears to be, as covenant buildings tend to be much more curved and human buildings wouldn't be so inset into the landscape.

Read, understand, leave.