Kidding aside, this doesn't make much business sense. A lot of people buy Macs and run Windows alongside OS X because their work requires Windows. Why would Apple remove that whole segment of the market from their purchasers just to save a few bucks on the chips? I don't think they will.
I also think this is slightly unlikely because it would probably require substantial investment in rewriting a lot of the plumbing for OS X (I don't know much about it).
And even further, why would they work on building their own chips like the A4/5 and then put in the effort to end up using someone else's? If anything, they'll either switch to something else just in the MBA's or you'll see A* chips in there or something.
Keep in mind Microsoft is also working on porting Windows to ARM. Ideally there would be some form of Windows 8 able to run on the new Mac's by the time the architecture transition occurs.
Kidding aside, this doesn't make much business sense. A lot of people buy Macs and run Windows alongside OS X because their work requires Windows. Why would Apple remove that whole segment of the market from their purchasers just to save a few bucks on the chips? I don't think they will.
I also think this is slightly unlikely because it would probably require substantial investment in rewriting a lot of the plumbing for OS X (I don't know much about it).
And even further, why would they work on building their own chips like the A4/5 and then put in the effort to end up using someone else's? If anything, they'll either switch to something else just in the MBA's or you'll see A* chips in there or something.