Apple Had Late Stage Prototypes of an AMD Fusion Based MacBook Air
If you are wondering why the Air wasn’t really revamped much this last time, it is because you are looking at plan B. Plan A was basically a low power Llano in an Air shell, and that would have been a really tasty machine.
This AMD based design would reportedly have had much more graphics (GPU) power, and lose only a little CPU power as compared to what was ultimately released. The "Llano" is part of the AMD Fusion platform which offers a combined CPU/GPU hybrid system:
Forget about the CPU (Central Processing Unit). Chipmaker AMD would like you to think instead about what it calls the APU, its Accelerated Processing Unit. The combo product uses a single die to contain, according to AMD, "a multicore CPU, a powerful DirectX 11-capable discrete-level graphics and parallel processing engine, a dedicated high-definition video acceleration block, and a high-speed bus that speeds data across the differing types of processor cores within the design."
Graphics (GPU) performance has been a stumbling block for Apple in pushing its laptop designs further. The MacBook Air was stuck on previous generation Intel chips for an extra revision due to the relatively poor performance of Intel's integrated GPUs. Apple finally upgraded the MacBook Air to Intel's Sandy Bridge processors in July.
Earlier this year, Apple had reportedly threatened Intel that they would abandon Intel's chips if the company was unable to improve their power consumption profile. AMD would be the logical alternative to Intel, and it makes sense that Apple would have fully explored its options at that time.
According to SemiAccurate, one reason Apple chose not to adopt AMD's solution was AMD's inability to supply enough of the required parts to Apple. SemiAccurate had previously claimed that Apple was also looking into moving from Intel processors to ARM processors in the future.