This thread's been dead for a while. I've been doing some homework (mostly because I am considering buying a house at auction that's in CDOT's eminent domain path).
Not sure we realized this, but the "Preferred Alternative Collaborative Team" has settled on leaving the highway in its current alignment. CDOT has pretty much committed to sticking with their recommendation, so it sounds like rebuilding the viaduct will be the preferred alternative.
The group couldn't reach a consensus on shift north versus shift south, but it sounds likely that the shift north is going to happen (CDOT will build a new elementary school to replace the one that'll be demo'd). Also, the dog food plant has tentatively agreed to implement some sort of odor control scrubbers - sounds like the neighborhood was going to push the shift-south option, which would require taking the plant, if they didn't.
This is going to be a much bigger viaduct the second time around...
Here's a comparison of that alternative (like to become the preferred alternative), with both the north and south shifts shown:
Here's a full presentation from the last meeting in July (big big file):