I liked your thoughtful analysis but I respectfully disagree with your opinion that "From a technical perspective, adopting ARM for SoCs makes little sense. It utterly eliminates one of AMD's core competencies, namely their x86 expertise." I think ARM is a better technical solution for tablets and netbooks/ultrabooks/notebooks because power consumption is critical in these markets. A successful company has to provide what the market needs even if it is not the sweet spot of their core competency. Otherwise, it is like being the guy who drops his keys in a dark parking lot and looks for them under a light instead of where he dropped them.

Here's my opinion of what AMD should do:
1. Make a tablet/netbook/ultrabook/notebook chip with ARM CPUs and ATI graphics.
2. Start work on a 4G wireless processor so in a couple of years they can offer a cell phone chip. This is totally doable at AMD.
3. Don't make an x86 + ARM chip. That's a dumb idea that no software engineer will like.
4. Bury the animosity toward Nvidia. It hurts the whole industry when there is no performance compatibility between Nvidia and ATI graphics.
5. Price the Opteron 6000 series at the same price per socket as the Opteron 4000 series to encourage more adoption of high socket count systems and high core count software optimized for AMD's microarchitecture.