Nvidia X1 already is 1 tflops GPU and the X2 (which is likely to be in the nintendo) is going to be around 1.5 tflops. Those are mobile SoC's with CUDA cores, fit OK in tablets (Pixel C has one), X1 peak power consumption is about 10 watts.
Xbox one GPU is 1.3 tflops and PS4 is 1.8 tflops. So in the same ballpark
Xbox one GPU is 1.3 tflops and PS4 is 1.8 tflops. So in the same ballpark