Theory: Wii U is part of the fusion concept and will be around longer than we think.

[teigaga]

This could make sense but not for their future home console.

Nintendo has every reason to jump the gun, just as the 360 did in 2005. The Wii U isn't underpowered because it came out a year early, its underpowered because nintendo designed it to be that way. Being the "most" powerful has never been that important. They simply need to be significantly more powerful then the PS4/X1. In a year with no competition and superior performance they could gain favour from third parties and consumers, whilst having room to rebrand themselves. Launching alongside PS5/X2 would just be a messy and following the Wii U they'd be last on most people's minds.

Also I think people are taking the fusion too literally. I don't see Nintendo letting their home console and handheld share the exact same library. Remember that in that diagram they had Laptops, not just iphone/tablets.