I don't see much sense in introducing an iMac with a smaller screen than the current 21". If the goal of the exercise is to get the price under USD 1,000 it seems like going with a cheaper display and only updating the innards conservatively would do the trick. Not that I myself would care much for such a product because the thing i love the most about my 27" iMac is it's gorgeous display.
If they keep with USB2 I also don't see the point in ditching FW. HD sizes have just become too big to comfortably shove data around over USB2. But hey, they could introduce FW3200, seeing how it's pin-compatible with FW800.
