Don't have high expectations this time so hopefully I am surprised.
In no particular order
MS
Fallout 4
COD could go to Sony
Assassin's Creed
The Division
Mirror's edge
Halo 5 Singleplayer and/or BTB multiplayer gameplay
Rise of the Tomb Raider (About time we see some gameplay)
Fable Legends (Could see MS pushing this to PC conference)
Forza Motorsport 6
Forza Horizon 2 free DLC
2 Rare Games 1 smaller title this year (Battletoads?) and a Banjo game next year
Gears Of War remaster Gears 4 Beta access
Gear of War 4 teaser
Something Minecraft related, Hunger games coming to Xbox 1 version of Minecraft?
Announcement of Hololens games 1 or 2. Minecraft probably 1 of them.
Short talk on Windows 10 update downloadable next month for preview members.
Sony
COD could stay with MS
Star Wars Battlefront
Destiny DLC
Batman Arkham knight trailer
MGS V
Uncharted collection they gracefully dodge the no multiplayer
but mention the pre-order bonuses and Beta access
U4 set piece or multiplayer demo
Horizon teaser
Persona 5
God Of War 3 remaster
Until Dawn
Project Morpheus announce a 1-2 game. They may do a demo but hopefully they don't.
Edit: Both will have Indie montages.