Digital Event for sure, it worked really well for E3 2014. Conference for E3 2016 and E3 2017 announcing the 3DS and Wii U successor.
Here's my prediction list for the Digital Event (in no order)
The Legend of Zelda Wii U - Trailer with Holiday 2015 at the end of it, and name unveil
Xenoblade Chronicles X - Trailer with NA release date
Yoshi Wooly World - Trailer with release date
Mario Maker - Trailer with release date
Star Fox Wii U - With First trailer and a Fall 2015 release date at the end of it
Devil's Third - Trailer with Holiday 2015 release date
Project Treasure - First Trailer and a release date frame
Metriod Wii U - Announcement Trailer, 2016 release
Animal Crossing Wii U - Announcement Trailer, 2016 release
Pokken Tournaments - coming to Wii U with 2016 release
New Nintendo third party saved title ala Bayonetta 2 and Devil's Third
New Mario Sport title - Wii U
Shin Megami Tensei X Fire Emblem - First trailer, 2016 release.
Wild Guesses
Paper Mario 5 - Wii U
Super Mario Galaxy 3 - Wii U
A new retro Nintendo revived series - Earthbound, F-Zero, Star Tropics, or etc
Project Ukelele (AKA The Banjo Spiritual successor) is Nintendo published
