Nintendo has been dropping hints for a while now, that they want to "tear down the barrier" with the relationship to TVs, (wii u gamepad) also making the box "invisible" (wii u console tucked away in adverts). The big N at heart, is a handheld focused company that loves to innovate in controls/how to play. Nintendo has considered the console box evil and yucky (IOW, expensive) for the last two gens, they are not making a comeback to that model as long as MSony are both around.
In fact Nintendo likely thinks the Wii U is also fat and ugly, they'd love to go digital or disc free. Ninty aims to be sleek, small as possible/blend in and just focus purely on the games. Talking power, it is pretty much guaranteed to be weaker than PS4, and it'll be lucky to sniff XB1 level to be honest. Nintendo will focus on 1080p/60 (forget 4k) for their main artstyle, so you can guess how much power they really need.
Soundwave mentioned for the Fusion idea, the console version can simply stack a few of the HH's chips. This should bring manufacturing costs down giving Nintendo a better contract, so there is potential for decent mobile grunt by '16-17. So let's say 3 HH mobile chips stacked in the home con. Now, you have to be realistic, how powerful would the HH be? The most generous prediction has been Wii U level. So Wii U x 3 would be near 1 tflop or still short of XB1.
It's all about profits for Nintendo this next gen, I doubt they get too funky with the extras, they'll definitely be making money out the gate and going mobile tech & same chipset for all their HW (could be more than 2 types) will help achieve that goal.
