I don't see why people are being so negative about this. The Wii U failed and the Gamepad concept failed with it. There is no reason to keep pushing a console people don't want. Nintendo's internal teams have moved on and will release a lot of games for NX. Everything is pointing towards a 2016 release. They are not going to do a Sega! Sega put out multiple add-ons to their hardware and released a new console at almost the same time. That's not what Nintendo is doing. The Wii U will have a shorter life cycle than usual, but 4 years is still acceptable.
If Nintendo has to decide between a healthy console business + some pissed hardcore fans ("no Wii U exclusive Zelda! Boo!") or bleeding money for years just to keep some fans happy, they should definitely take the first option.
The fundamental problem here is that Wii U's install base is so small, it is hard for Nintendo to make a profit with their games. Pikmin 3 sold less than the Gamecube games but was certainly more expensive to develop. Most games sold less than their Wii and Gamecube iterations but had higher dev costs. The Wii U only has 10 million sellers so far. Sure, they can get along for another year, but what are they going to do in 2017 without a new console for the first 11 months of the year? They would also have to postpone the 4DS launch to 2018 in that case and the 3DS is not gonna live that long with sales regularly below 100k units per week already. Nintendo needs to get their new hardware out in 2016 (+ handheld in 2017) or they risk sliding back into red numbers. That's just the way things work in the console business: The older a console gets, the less software it sells. VGChartz had some great graphs and analysis illustrating this back in the day.