I hadn't seen this, but this article was published 10th of Jan 2015:
http://www.eurogamer.net/articles/digitalfoundry-2015-in-theory-nintendos-next-gen-hardware-and-the-strategy-behind-it
"Around 18 months ago, during an informal chat with an extremely well-placed individual in the hardware manufacturing business, an interesting nugget of information dropped into the conversation - Nintendo was already accepting pitches from third parties on the hardware make-up of its successor for Wii U. Two names were mentioned: AMD and Imagination Technologies, creators of the PowerVR mobile graphics tech. With the lack of backing sources, that little aside never made it to print, but as Nintendo strives to bounce back from the Wii U sales disappointment, eyes inevitably turn towards future platforms."
So no mention of IBM or NVidia.
For the record if Nintendo went with AMD they could still have an ARM CPU, depends on when K12 is going to be ready, but given that 3rd party asked Sony and Microsoft to go with X86 and Nintendo were making decisions based on 3rd party input it seems highly likely that X86 would be the CPU of choice for a new console.
I hope Nintendo doesn't wait too long after E3 to announce NX and announce exactly what NX is and what tech it's using.
