The next nexus is likely to use the OMAP5 which is also cortex a15 and uses a powersgx544mp2 clocked at 500mhz vs 200mhz in the powersgx543 in the a5 which is clocked at 200mhz. The architecture has most likely seen improvements as well. Google likes texas instruments as they are very open with their devices and provide lots of useful documentation to devs and are for the most part open source.