Actually predicting what will be there:
Sony: Shit, and you know it. Ratchet is done now, so there showcase will just be Dad of War, some Soy movie title, and capeshit/licensed games. Prepare to see Spider-Man 2, Hogwarts Academy, The shit blue-people Avatar, and maybe Wolverine. If we are really lucky, the rumored PS All-Stars 2 will happen to jump on the Smash train. That or Sackboy 2, please have Sackboy 2.
Microsoft: "We bought companies", "Gamepass", "We will have games...eventually", "Halo", "Forza." Did I get it all?
EA: "Please buy us Disney!!", "sports game", "Star Wars", who cares...
SEGA: Sonic Origins and Frontier get shown more, maybe Yakuza, maybe Monkey Ball? Not much more past that.
Warner Bros: Shows off more Suicide Squad and Gotham Knights. Multiversus gets a trailer. Injustice 3 gets announced. Finally, we may learn what Tt's next LEGO title is.
Ubisoft: Assassins' Creed, Far Cry 6, Tom Clancy, Just Dance 2022, and Mario + Rabbids.
Nintendo: Expects praise when they announce Daisy will come to Strikers a month after launch. Will show off the sky area of BOTW2. More info on Splatoon, probably will show the Mad Max-esc apocalypse single player. We will get small teasers for FE Warriors, Advanced wars, and Strikers. New MK8 DLC will release shortly after presentation. One surprise announcement. Only other possible things are Bayonetta 3, which is possible given it already had a teaser, and Metroid Prime 4, which is highly unlikely. Rabbids will probably be mentioned, but get main spotlight at a Ubisoft show.