Making a successor to the Wii U too early on is a big mistake.
If Nintendo releases their next home console in 2016, then it will likely be less powerful than the PS5 and Xbox 4.
It will continue the cycle of underpowered Ninty consoles that launch too early and lack third party support. It would be better, imo, that Nintendo continues to support the Wii U with games up until the end of the PS4 gen. And then they need to consider making a console that is at least as powerful as the PS5 and with a similar architecture so that third party publishers will have no reason to not support it with their games. Also, Ninty needs to improve their communication with third party publishers.
Either that, or Ninty should continue to support the Wii U and then work with Sony on the PS5. They don't have to be involved in the hardware, but they can become a major publishing/development arm for Sony.
Or Ninty can go work with Valve on the Steam box.