I anticipate the reveal of new playable characters, and we might possibly see the full roster, like we did with Mario Kart 8 before that came out. I wouldn't be surprised to see some revealed villains playable as this point, namely the humanoid ones, and while I don't particularly care to do so in most cases, you can be sure even seeing Ganondorf will tickle my fancy.
Aside from that, most of what we hear I think will be explanations on what the recent Japanese-exclusive streams have detailed on, such as the Gold Skulltulas and item management. I'm not sure how long the presentation will be, but receiving a large amount of gameplay will be great for fueling the hype.