I think it needs to be completely redesigned from the ground up. The current design was intended for a thicker notebook. When they made it thinner, the design and materials don't work as well. I'm thinking about the way the hinge is restricted because of the thinness of the case and also the way certain parts are prone to buckle because of how narrow the strips of aluminum are: like above the latch button and around the DVD slot.
In addition to changing the material to something more durable and suitable for the thinness of apple's laptops (like the material thinkpads are made of - some kind of magnesium composite) , I'd like to see improvements in ergonomics:
1. a display that can be adjusted up and down for more comfortable work position
2. A trackpad button that is easier to click and with more feedback in the actual clicking
3. The ability to listen to music with the case closed in a battery-saving mode.
4. I'd love a detachable keyboard - coupled with the adjustable height LCD would be an ergonomics breakthrough for a notebook computer.
5. Keyboard keys capable of displaying different information depending on language you're using and other preferences - backlit LED. The keyboard layout could then be completely adapted depending on usage.
6. User upgradeable hard drive -something you can swap in a couple of minutes
7. The same magnetic closing mechanism as the macbook. If this is not going to happen, at least change the release button so that it my relatively small fingers can press it comfortably.
8. A good quality, 8-bit display with even backlighting, good viewing angles and NO grain.
9. And then all the usual improvements: better battery life, better GPU, faster CPU, higher ram limit, better sound etc etc
And all this for the same of lower price! I can keep on dreaming....