Also, if the "A5 is SoC including RAM", then the RAM is on the same piece of silicon as the ARM core (for it to be SoC). Not sure how it's possible for Samsung to make part of the silicon (for the core) and someone else to make the RAM. Perhaps the RAM isn't on the A5 after all ;-)

There's no risk in Apple switching manufacturers (e.g. Samsung Nexus uses a TI OMAP SoC CPU, instead of a Samsung Exynos for the Galaxy S II). Switching to Intel is the massive risk, since they don't use ARM cores at all, so the O/S would require a rewrite.

Finally, the Ivy Bridge microarchitecture isn't aimed at lower power computing (Intel Atom chips are based on the Bonnell microarchitecture), so there's unlikely be 3D transistor technology...

Apple's real move would be to drop the A6 entirely and focus on the same CPU's used by Android, since the both Android and Apple are using ARM V7 instruction sets with Cortex A9 cores.