I think Nintendo is trying awfully hard in their R&D to concoct a creative, innovative interface that would revolutionize gaming much like the Wii remote + nunchuck did. It will probably be something no gamer has never dreamed of. I think Nintendo is going go all out "risky" and "experimental" on their next console because they really don't have better options. That's the mindset they had with the Wii and it worked. I believe they will definitely have that same mindset for the next console. Nintendo knows that they need a new 'hook', that is the only way for their next console to succeeed.
Although Nintendo was smart enough to know they need to differentiate themselves from their competitors, Nintendo made a big mistake thinking the Wii U gamepad would be an interesting 'hook' to pull in the Wii owners and new owners en mass. The thing wasn't/isn't appealing to the mass market, it was too safe and lacked innovation.
I also think hardpower is largely irrelevant (the fact that Wii sold 100+ million and Nintendo handhelds have always outsold their competitors with more powerful hardware is very telling) and Nintendo knows it so I suspect the Wii U successor to be roughly the same power as the Wii U to keep cost down.
I expect to be wowed on 2017 with Nintendo's next console.







