Seems like much of it keeps leaking, whether intentional or unintentional. It's hard to stay excited when everything keeps leaking out prior to the event.
Sony has said their presentation is going to be a bit different this year, choosing to focus on deep dives of Spiderman, Ghost of Tsushima, Death Stranding, and The Last of Us Part 2. I'll be shocked if this is ALL they show. I can't help but think they have more up their sleeves than this. There are other games in development, this we know for sure. There's Concrete Genie, Dreams, Medieval Remake, etc. Plus I'd say we'll see more of Call of Duty BOPS 4, maybe the rumored Rocksteady Superman game. Maybe some more of Red Dead Redemption 2.
Nintendo has said they are only focusing on 2018 titles, which would be Smash Brothers, Pokémon Let's Go Pikachu & Let's Go Evee, Yoshi, Mario Tennis Aces, and the new Fire Emblem. If the leaked rumors are true, we should see Dragonball Z Fighters, Paladins, and Fortnite announced for Switch as well.
Microsoft to me is the biggest question mark. Of the 3, they have been the most tight-lipped. Everyone assumes that Forza Horizons 4 will be shown. Crackdown 3 I'm sure will make an appearance. Ori and the Will of the Whisps will be there. I wouldn't be surprised if Halo 6 is at least teased. I also have a feeling they'll lean heavily on 3rd party games like Anthem, Cyberpunk 2077, Battlefield V, Assassins Creed Odyssey, Shadow of the Tomb Raider, etc.
