i think it'll come out to $120, which i think is a pretty good deal. they'll probably try to make the bundles more competitive:
Arcade Slim (w/out hard drive or WiFi) for $150
Arcade Slim Natal/Kinect Sports for $250
Elite Slim Natal/Bundled games for $350
This would be a good way to undercut Sony for the holiday, and at the same time have the lowest cost of entry.
Microsoft is phasing out the older model, and looks like they are going with one base model. In the arcade units they have had, they had to put internal flash memory to be able to account for OS updates. So, the question I will have is, if they are likely to have one model, how will they release an arcade system without any form of storage for O/S updates? I would say that it is likely all 360s will have some form of harddrive for them at this point on, and still keep the Wifi with it. It is possible you get a 360 low end unit with a 60 GB HD at $200. Kinects sells in the $100-$120 range with a game or two bundled. There will also be a 250 GB $300-$350 model.
Or Microsoft then sells Kinects for $100, the current model with Kinect for $300, or without at $200.