The more research I do the more I'm convinced Nintendo could have a very high end portable that could handle even PS4 ports at 960x540 or even 1280x720 in some cases without it costing a huge amount. It would be more like a return to the N64-GameCube era of powerful but affordable.
The Apple A9X chip is about 600 GFLOPS and it's *not* an expensive chip, the 16-core (higher end) PowerVR 7900 versions of it (which is 800 GFLOPS) is being designed for budget/low cost Android set-top boxes.
Likewise the Tegra X1 which is Nvidia's kinda opponent to the A9X/PVR7900 is 500 GFLOP and has been in a $199.99 console for like a year already, and that device is sold at a fat mark up too.
If Nintendo could combine their 3DS userbase size with a modern chip like the Power VR 7900 or Apple A9X type processor (which I'm projecting costs about $50-$60 at cost), a lot of developer support would follow because developers could port their PS4/XB1 engines over.
That's probably still their best bet. The portable is should sell at least OK (50m-60m) even with erosion from mobile and this would differniate their portable from mobile much moreso too by being able to run real console games on the go. The console would then be more like just a bonus.







