Perhaps Apple will add a 10" or 11" MBA Light to the lineup in order to compete more closely with the Sony TZ (and other ultraportables) in terms of footprint.
I don't think Apple will do that, since the focus on thinness over footprint is part of what differentiates the MBA from other ultraportables. Making a smaller footprint would require the MBA to be thicker, which would require a complete redesign. However, I would like to see a 12" MBP as much as everyone in that camp. I think it would be great if Apple came out with a 12" MBP to satisfy the footprint-focused power users and kept improving the MBA as the ultralight, ultrathin laptop that it is. We'd have the best of both worlds. I'd have a hard time deciding between the two when I came to the checkout, though....