Apple is likely to stick to a single core SoC but switch from Cortex A8 to Cortex A9 as it moves to the iPhone 4; the A8 has been used in the iPhone since the 3GS and is also present in the Apple iPad.
Many competitors are moving away from single core processors to dual core models and at least two models - the Motorola Atrix and the LG Optimus 2X - have already been announced at CES 2011.
On the other hand, moving to dual core increases power consumption (and associated costs) and decreases battery life. Sticking to a single core SoC configuration makes sense especially as the A9 provides with 25 per cent extra performance than the A8 per MHz according to ARM.
Even if Apple sticks to the same clock speed (1GHz) as the iPhone 4 (and same thermal envelope), the Apple A5 should be able to provide double-digit performance improvements simply by shifting to the newest Cortex A9.
The other way of reducing manufacturing costs and improving power dissipation is to opt for a 32nm or 28nm manufacturing process. In contrast, the current Apple A4 processor is built using a 45nm manufacturing process by Samsung.
The Series5 SGX will face some serious competition in 2011 from the Geforce ULV (Tegra 2), the Adreno family (Snapdragon) and the Mali series (Generic ARM) and we already know that while the SGX535 has done a great job until now, it set to be replaced by something better.
We don't expect Apple to go multicore for when it comes with graphics as it would have a negative impact on power consumption, heat dissipation and battery life.
The most likely option for Apple would be to use the PowerVR SGX540 which is used in the Samsung Hummingbird processor that powers the Nexus S.
The catch though is that, while the SGX540 is more powerful than most graphics solutions on the market, it will be superseded by the Adreno 220 and other solutions shipped in 2011.
However, one might argue that Apple has been able to do incredible things with the SGX535, a chip that was launched back in January 2007. What does that mean? Well, the iPhone 6 is likely to be Cortex A15-based and come with the PowerVR Series6.