Apple Product Roadmap – Power efficiency favors ARM over x86

ARM chipsets are more efficient than x86 when using equal geometries, making ARM chipset less reliant on smaller geometries to sustain efficiency improvements. ARM’s main weakness has been processing power, but this should be addressed by the move to 64 bit processing in late 2013 as shown in the ARM performance roadmap in the figure below.
ARM Roadmap
ARM’s power efficiency could stay higher relative to Intel’s Core chips for next several years. While Intel should bridge the power efficiency gap meaningfully with the launch of its Haswell processors next year, we believe power efficiency improvements in successive chips will be incremental and mostly dependent on die-shrinks. Therefore, the ARM roadmap appears to offer advantages over that of x86 chipsets that Apple may prefer.

What are the Possibilities of Hybrid Chi Models ?
ARM processor speeds still need to improve and Intel may find alternative ways to improve performance. For example, Intel may look to create a hybrid chipset featuring both an x86 and an ARM or MIPS processor. MIPS is an alternative to ARM that Intel recently licensed. Such a solution may push out the timetable for a transition by Apple to ARM but may not change the long term trajectory.