As a disclaimer I will say I don't think all of these things will happen, I know in the past people have mistaken my comments for me making out that all of my guesses will definitely happen, I don't think they all will, but I think some of these could happen.
For PS4: Bend's new IP, God of War 4 (or whatever it's called), the rumored Exclusive Spider Man game (perhaps made by Sucker Punch, as they're awesome at making superhero/villain games), Eight Days, The Getaway, maybe a new Sly Cooper and a new game set in the Hawk Series (like Starhawk, but with an epic single player campaign).
Oh yeah if Take Two are going to be having their own conference then perhaps this could be the time to reveal Agent as a PS4 exclusive James Bond game.
I'd love to see a futuristic From Software game, with the studio building on the formula they used for Souls and Bloodborne.
Would love to get an announcement from Ready At Dawn, like another game in The Order series, that takes it's queues from Uncharted 4 and The Last of Us in the gameplay front. Maybe set in a more open city.
Failing that maybe they have been working on another new IP, would be cool to see how the studio has moved forward after The Order.
Nintendo: NX hardware officially shown, new Metroid, 3D Mario, Wave Race and F-Zero and a bunch of new IPs that are targeted at the western 3rd party market.
Beyond Good and Evil 2, along with a remaster of the original for NX would be nice.
For Xbox One: New IPs that move Xbox into some new areas, like bringing the platformers or some action adventure titles, maybe some classic under used franchises like Blinx, a Banjo game, new Jade Empire.
Xbox doesn't need to keep leaning on Halo and Forza, maybe a new Project Gotham game would be nice as a change of flavor.
I hope all 3 platform holder's bring it.
For 3rd party, it would be cool to see a Watch Dogs sequel, new Splinter Cell, Prince of Persia, finally have a reveal for that Visceral Star Wars game.
New IPs would be cool.
Hopefully CD Projekt Red can finally show something of Cyber Punk 2077.
A new Red Dead for current gen consoles and PC.
The main thing I'd love though is to see surprises revealed, with gameplay.
