I both agree and disagree with you: I think that the next iterations of both Nintendo home and handheld consoles are going to be designed to work incredibly closely with each other, and I wouldn't be suprised if the next handheld comes before the new console and works as intended with the Wii U.
However, I also think that ~2017 we're going to get the new home console from Ninty and it'll have considerable horsepower; representing a halfway between the PS4 and PS5 (same as the Wii U). Not so much for Nintendo's purposes, but to enable 3rd parties to play along.