If what Emily said about Nvidia being involved is true, i think all the pieces of information we have would fit together.
- AMD has 3 wins: 2 x86 and 1 arm, one of them goes beyond gaming. These are PS4 Neo, new Xbox One and an Apple device. Neo and 1.5 technically aren't "new wins", but maybe it's something that they can spin (especially if the revisions use Polaris). It would also explain why they only expect 1.5b revenue from these.
- In late 2014-early 2015 (iirc), Nintendo was looking for Lead Graphic Engineer for Next-Gen Console. Experience with low power architecture was a bonus, and Nvidia GPUs are very power efficient (much more than AMD up to Maxwell vs GCN 1.2, we don't know about Pascal vs Polaris yet).
- LCGeek reported that the Nintendo NX CPU, while far from being a monster, is considerably more powerful than what the Xbox One and PS4 have.
- Emily Rogers said that the CPU isn't x86 and the specs on paper are closer to Xbox One than PS4, and "even that would be a stretch".
- If Nintendo went ARM+Nvidia, the above situation should be pretty clear even in the more pessimistic scenario. A 1tflop Nvidia GPU has lower numbers on paper but it absolutely destroys the Xbox One and comes pretty close to what the PS4 has (a 750ti, which is 1.3tflops, actually beats the PS4 in many situations as per Digital Foundry's tests). But isn't this a bit disappointing? A console that comes out in 2017 isn't considerably better in every way than two consoles that came out in late 2013? The answer should be yes, but there's another thing to consider: as we've seen many times, the CPU in the PS4 and Xbox One is a bottleneck, especially in certain scenarios. Nintendo hates bottlenecks, and especially after the harsh criticism they received for the Wii U CPU, they probably wanted to balance the new console in a way that the CPU would never be an issue compared to the performances of the GPU. So if the GPU is 1tflop Nvidia, it falls between X1 and PS4 in real world performances, but something like the much speculated 8 core ARM A72 2GHZ would never be a bottleneck for that kind of performance. If the GPU was much more powerful than the PS4 though, they should've used a much more powerful CPU to avoid bottlenecks, otherwise CPU could still be a problem. Which would have probably brought the price higher than the one they wanted to set (and let's not forget that they don't want to sell the console at loss).
- ARM+Nvidia on both consoles means that they have to build only one OS and cross development between home and portable is as easy and streamlined as it gets (especially if, with tegra, the portable performances are better than expected). We speculated many times that AMD didn't have anything in the ultra low powered space and that could've caused issues (or Nintendo going with PowerVR for the handheld), but Nvidia does.
- Iwata said that the NX is being developed in a way that every future console will be natively compatible with the already existing games to avoid software droughts at launch and build a giant library of software. Many people said "but AMD is in dire financial straits, what would happen if they go bankrupt?". Maybe Nintendo thought the same thing and this was one of the reasons why they decided to go to Nvidia.
- On the other hand, Nvidia, unlike AMD, isn't known for its low prices. It's possible though that they wanted a big client for their Tegra line, so they gave Nintendo a killer deal for that and decided to settle for a low price (on par with what AMD would've asked?) for the home GPU as well. That's if the home doesn't use a very high clocked Tegra X1 (or the new Pascal version).
The only thing that still sounds weird to me is that Nintendo would think about ending their collaboration with AMD and give up to their low prices, but maybe the reasons above were enough to switch sides and Nvidia might have helped if they really wanted that Tegra win, with the expectation of higher margins in the future.
Interesting, do you have a source for this?