Even at 14nm, its unlikely. Samsung Galaxy S6 already has some troubles to maintain its GPU clockspeed to 770mhz, making it a 192gflops part without throttlinh to 400mhz or so.
I feel like gflops are meaningless when we start talking about different architectures. What is in the S6? Mali? I highly doubt that pushes as many triangles (among other things) as even a severely underclocked Radeon.
Still, I agree. Clocks need to be low, although I feel like Japan might be accepting of an IPad Air-sized tablet. Even that one investor was asking for the 3DS to have screens a full 2x as large last year. That gives them a little more wiggle room.
The other thing we need to talk about is aspect ratio. There is no guarantee that it will be 16:9. Ipad Air is 4:3 and cell phone games often use vertical orientation. This does not stop devs from making games multiplatform in the slightest. 1024x768 is possible and probably very cheap at the right screen size.
Vertical orientation would also be key for 3DS BC, which they would be wise to include...