> If you were looking at >100,000 chips it might be cheaper to just design your own core.
It's not just about building a processor core - that's relatively easy and has been done multiple times in the past by a whole variety of companies (ARC, Tensilica, etc).
The more expensive part to reproduce is the software - providing a production quality tool chain, debugger, other development tools (valgrind, etc), operating system support, optimized codec libraries, etc is _far_ more expensive than actually developing the CPU hardware.
I suspect one of the big reasons behind the ARM success is that it isn't just about ARM - it is really about ARM plus more or less the entirety of the rest of the silicon tech industry collaborating on a huge amount of the software and supporting infrastructure. That's almost impossible to reproduce outside of ARM and x86 (and to some extent PPC) - they have a 20 year headstart on everyone else ... and it costs a huge amount of $$$ and time to close that software support gap for any new architecture (which is one reason why Itanium never got off the ground - the software infrastructure just didn't exist to support products using the CPU).