I know this is OT sorta but OP mentioned it. People didn't really think a new Zelda was coming this year, did they?
Well, Nintendo gave us a reason to believe it was. They confirmed its release for 2015 at E3 2014 in June, then they confirmed it again in December 2014 during the VGAs where the gameplay footage was shown, but filmed from a distance. The game was also confirmed twice on both occasions to be playable at E3 2015.
On a personal note, I didn't initially expect Zelda Wii U to be released in 2015, so when Nintendo announced that it would be during E3 in June 2014, I was surprised. This was due to the Zelda Team's busy schedule with other Zelda titles...
A Link Between Worlds initially began development with 3 staff members by the end of 2009 (which was before they new that the 3DS would have the 3D effect capability), but after 6 months of brainstorming and initial prototyping, the game's early progress was basically trashed by Miyamoto. By the second half of 2010, the game was set on using the wall mechanic to base the game around. By October 2010, the game's early development was put on hold not long after a prototype was made for it (which assets from Spirit Tracks). Nintendo needed to reassign the staff members working on A Link Between Worlds to be put on Wii U launch titles instead.
Eiji Aonuma and the rest of the Zelda team were busy working on Skyward Sword, so he did not personally join the project for A Link Between Worlds until after Skyward Sword's development was finished around November 2011. By May 2012, the dev team working on ALB made a couple of small dungeons, but Miyamoto didn't like them. He then suggested that the game be based on A Link To the Past. However, both Miyamoto and Aonuma had commented years before about considering making a a game similar to the design of Link to the Past. By the end of 2012, development on the game ramped up, adding many more staff members to the project in order to get it released in time by the end of 2013.
Wind Waker HD used a small amount of staff members and development was said to last between 6-7 months in 2013.
As for
Zelda Wii U, development was confirmed to be in the works back in January 2013 along with Wind Waker HD. The small amount of staff that worked on Wind Waker HD and A Link Between Worlds eventually reunited to work on the rest of development on Zelda Wii U before the end of 2013. It was surprising to me that they managed to get the game shown at E3 2015 with an actual trailer with brief in-game footage,bu most of it was just a cut scene once Link rides off on horseback off-screen into the forest.
