My thoughts on the subject are thet they are probably going to make the display settings with a slider or some sort of selectable thing-a-majig wich will let you use DX7, DX8 or DX9 graphics. I'm not sure about DX9, but a lot of the screenies look like they're using the latest and greatest DX, however, most cards don't support it.
What I'm trying to get at here is that they will probably have a feature on there that will dumb down the graphics insanely to make the game playable on a dinosaur of a computer. It'll probably look like Doom I or II, just with the recreated monsters and whatnot.