So I'll be looking for/at:
-Metroid
-Mario. I'm completely sold on it and don't really want too much gameplay from it. Perhaps I'll leave the conference more clear on how I feel about exploration/adventure Mario returning.
-XB2. The game did not impress me in January. The landscapes and music I trust to be beautiful. I didn't like the character art or the limited dialogue we got. So if I walk away with a better impression of the characters and story from E3, that's positive movement.
I'd also like to see evolution of the combat system. I think it falls short as an action system and as a party-based system. It is good for mmo-lite, and I mean that seriously. The characters/roles are more distinct and defined and different to play than in most such games. But I really think unless you turn such a system into rts-like micromanagement or automation, it is never going to live up to such a game with other players or the extent of team control in a classic JRPG. And then, you can't build on that towards better party play, starting from behind.
I'd like to see XB push into action, turn-based, or a heavier tactical real-time system, personally. I doubt it will, but I'll be curious what they do do to the battle system.
-Japanese third party games: I'd like to see JRPGs, VN/adventure games, and action games announced and/or shown for Switch targeting 2018.
-2018 first party games. What is Retro working on? How does FE look?
-VC plans. Date, GCN, general look at how well it'll be supported.