Eiji Aonuma famously promised a 2015 release for Zelda Wii U at both E3 2014 and five months later at Geoff Keighley's Game Awards. He was quite adamant that he would deliver on this promise last December.
He already knew he was lying.
The story goes that after deciding Zelda would be delayed by a full year a few months into 2015 (hah!), Nintendo tapped Tantalus to give Twilight Princess a nice HD sheen on Wii U to fill the gap. It makes sense, after all it was said that Wind Waker HD only took about six months to make.
Here's the fatal flaw to that naive theory: Tantalus began hiring for their then-unspecified Wii U port in January... 2014. There are multiple sources agreeing on this, although the original links are dead. Tantalus hasn't released any new games since then, so what were they hiring for? Must have been Twilight Princess HD. Nintendo put them on it before Zelda Wii U was ever seen by the public.
Well, okay, maybe I'm making too many assumptions here. Maybe Tantalus was working on a project that fell through, never materialized. Besides, even if they were working on TPHD back in 2014, it doesn't prove Nintendo knew Zelda Wii U would be pushed back, right?
This is where it gets nice and meaty. Just this past February, the CEO of Tantalus stated on a podcast that said Wii U port would be released this very year. Is there any doubt now? Nintendo contracted Tantalus to remaster Twilight Princess for Wii U, and as of 9 months ago the planned release window was... basically on top of the supposed planned release window for Zelda Wii U.
Nintendo never planned on releasing Zelda Wii U this year. They knew a long time ago that it would be a 2016 game. So why lie? Just to drum up excitement for their home console last year? Uh... yeah?