Nintendo has announced that the upcoming Zelda game for the Wii U has been delayed until 2017, when it will launch simultaneously on both the Wii U and as-of-yet unseen NX. No specific date has been announced at this time, though the NX itself has been confirmed for a March 2017 launch.
Nintendo has also announced that, since the NX will not be shown at E3 this year, Zelda U will be the focus of E3 2016. The last time Zelda U was featured at an event was at The Game Awards in December 2014.
Update: It has been announced by a Nintendo press release that the only playable Nintendo game at E3 2016 will be Zelda U.