One word: CLOSEOUT
Haha. That would sting.
But why would they discontinue the air if it still sells unless Steve is utterly embarrassed by their performance? I think we will see an update with matte and no glass (too heavy), slightly rearranged aspect ratio to make it smaller yet still accomodate the full sized and Apple-standardized keyboard and glass trackpad, and 4 GB of Ram. I can't speak to their processor/graphics design as I'm not following chip development. I think battery life will be improved but not at the cost of added weight.
I do wonder if they may reposition the Air in the line up though. As it stands now I view the laptop line up as such:
Macbook - entry level laptop to hook new customers and college students on OSX and Apple design.
Macbook Pro 13" - the portable and affordable MBP with decent performance.
Macbook Air - stylish and functional but with tradeoffs (high cost, lower performance).
Macbook Pro 15" - the sweet spot of usability, portability, with maximal performance.
Macbook Pro 17" - same as 15 but a better desktop replacement in the absence of a stand alone display
I think the Air could REPLACE the 13" (even with a loss of 1-2 inches of screen real estate) if it simply upped its processor speed, had comprable graphics to the macbook (this is what Apple has been waiting for is my impression - e.g. NVIDIA/Intel issue), and the lovely and requisite 4 GB of RAM. Forget 8.