Apple isn't going to change its strategy with the MBA if it plans to update it soon. Apple has a history of using the same internal strategy with the 13" MBA, 13" MBP, 13" MB, Mac mini, and 20/21.5" iMac. I fully expect a new MBA with a C2D and Nvidia 320m before or at WWDC.
If Apple doesn't update the MBA before or at WWDC I would be shocked. Any MBA coming later in the year will not be able to use the C2D as Intel is done manufacturing them at the end of 2010. At that time, I still see Apple using a low voltage CPU and not an ultra low voltage CPU. Also note, Intel's next generation 32nm mobile CPUs have 2X the GMA IGP capabilities. Apple might go with the Intel HD as sole graphics then... it's almost forced to either do that or go AMD. It seems obvious the dedicated graphics will not fit in the MBA, as if it did I believe the 13" MBP would have gotten the dedicated first.