Talk--or speculation in this case--is cheap, but it's a starting point. Only Apple knows what form the next MacBook Air will take but big hints are out there already.
Intel's upcoming 45-nanometer Montevina mobile processors are strong candidates for the first refresh of the Air. Currently, the Air uses special 1.6- and 1.8-GHz "Merom" (65-nanometer) processors that use extra-small 22mm sq. packaging (see accompanying graphic) to yield a Thermal Design Power (TDP or thermal envelope) of 20 watts.
This class of small form factor (SFF) processors will also be part of the "Penryn" Montevina platform that will include the SP9400 (2.4GHz, 6MB L2 cache, 25 watts), SL9400 (1.86GHz, 6MB, 17W), and low-power SU9400 (1.4GHz, 3MB, 10W), according to a report in DigiTimes. The upshot: faster processors and better graphics--the latter also part of the Montevina platform.
Another piece of hardware that will likely be updated is the solid state drive (SSD). Samsung makes the Air's current 64GB SSD, according to the System Profiler utility (part of Mac OS X) which lists the model as "MCCOE64GEMPP." Samsung is already on the record saying it will bring out a 128GB SSD in the third quarter. It would not be surprising to see this become a part of a future MacBook Air configuration.
Intel's Montevina processors are due in May.