I think i read an interview where Aaron Greenburg (MS) was saying that they were "looking into" coming out with a cheaper Slim Unit, which means it wont have all the same internal components as the currently released slim. And knowing Microsoft, they're gonna find ways to cut the costs so they can sell it at profit or break-even. Also the fact that they are now allowing external USB flash drives to essentially replace the need for hard drive makes me feel that they are gonna continue with a hard-drive-less SKU to give them the advantage of lowest-entry cost SKU.
If I was MS, i would introduce the new Slim SKU for $150 around early fall (in time for Halo Reach), and cut the Elite SKU by $50 to $250 for a $150/$250 tiered pricing; then introduce bundled Kinect SKUs for $250/$350 with Kinect's launch (Nov 4th)
