Exciting times! Particularly pumped about the 3DS game news since I don't have a Wii U right now.
There's a few common possibilities that have been thrown around on this thread: Metroid, Mother, and Majora's Mask. Coincidentally, Earthbound, Majora's Mask, and Super Metroid are all in my top five games of all time, so if a game from any of these IPs gets announced, I'll be ecstatic.
A new 2D Metroid has been wanted by tons of people. The rumored/cancelled (?) Metroid Dread has been the dream of many and that would be absolutely brilliant if they announced it or something similar. The only "hint" we have received is that Reggie will be wearing a Metroid-related pin tomorrow (he wore a Mario one today). Maybe he just likes the look of it, but I guess you could count that as a clue.
An Earthbound Trilogy would honestly be the best thing Nintendo has done in years, in my opinion. Earthbound is my favorite game of all time and I love the other two. Whether it's a complete remake or a set of ports, there's no way a collection couldn't turn out to be incredible. In the Nintendo Digital Event video, as many before me have said, Reggie "burns" an audience member demanding Mother 3. It's notable that the same fan requested Star Fox, and look what we got. It's also notable that the segment was created by Robot Chicken, a comedy series. Maybe they just created the joke because they're... comedians. I guess Nintendo could've told them to say that on purpose, but I don't know. Reggie said in the IGN thing regarding Mother 3 that they let fans know they are aware of such demands and he wasn't going to make any announcements. So, Earthbound Trilogy? Hopefully.
Majora's Mask 3D. The most likely contender. Grezzo has been quiet for awhile now. Majora's Mask used a ton of OOT's assets so it wouldn't be too much of a task, like creating a brand new game. There has been the ALBW MM tease, magazine (I think) teases, and now today, Zelda Williams' tease. That Zelda holding Majora's Mask is a pretty big hint, in my opinion. It looks professionally made. Maybe she knows someone really good at designing things like that, who knows. The main issue with the idea of Majora's Mask being announced is that how are they going to spend 90 minutes talking about it? Many people have played Majora's Mask and know what OOT is so they have an idea of what a Majora's Mask remake would be like.
Personally, I hope it to be a Mother Collection, but that "tease" was just most likely a lighthearted joke from Robot Chicken. As I said earlier, if it's any of the three titles above, I'll be ecstatic.