Many things were hinted/leaked before hand, not just for MS but Sony too. However, from the same sources, some things did not show up. Trying to remember everything

Red Dead Redemption 3

Knack 2

A new Forza (aside from Horizon 3)

Did I miss anything? I think there was more

That Suikoden VI rumor.

Wait, a new Forza besides Horizon? Why would people expect that? Forza Horizon and Forza Motorsport are biennial alternating entries, and the last one was Forza 6...

The Xbox Live will be free rumor.

The people holding on to all the MS leaks hinted at a new Forza series being revealed

people were speculating it was moving to a 3 year cycle. So something like Horizon - New one - Motorsport, repeat

Not a solid rumor, just wishful thinking, there was nothing that even hinted at it.

Sucker Punch making Spiderman PS4 Exclusive.

Quite impressive, but wrong developer.

Yeah but that one was "fixed" several days before E3, we already "knew" it was Insomniac from an actual insider, SP was just the name fans came up with to explain Sony making an exclusive Spider man game.

Rumors that did come true:

Prey 2 will be revealed at Bethesda's E3 conference - Link
A new Quake will be revealed at Bethesda's E3 conference - Link
Wolfenstein: The New Order 2 will be revealed at Bethesda's E3 conference - Link (only hinted though)
The Elder Scrolls V: Skyrim Remastered will be revealed at Bethesda's E3 conference - Link
God of War IV will be revealed at Sony's E3 conference and take place in Norse Mythology - Link
Sony Bend's new PS4 open world game will be revealed at Sony's E3 conference - Link
A Spider-Man PS4 game possibly developed by Insomniac will be revealed at Sony's E3 conference - Link + Link + Link
Horizon: Zero Dawn will be demoed at Sony's E3 conference - Link
A new Crash Bandicoot PS4 game will be revealed at Sony's E3 conference - Link
Kojima's exclusive PS4 game will "keep coming" back with more details - Link
Forza Horizon 3 will be revealed at Microsoft's E3 conference and take place in Australia - Link
Dead Rising 4 will be revealed as an exclusive at Microsoft's E3 conference - Link
State of Decay 2 will be revealed at Microsoft's E3 conference - Link
Gwent: The Witcher Card Game will be revealed - Link

Rumors that didn't come true (only a few rumored to be present at E3 though so there's still hope):

Red Dead Redemption 2 will be revealed at E3 - Link
Agent will be re-revealed at E3 - Link
Grand Theft Auto IV Remastered will be revealed at E3 - Link + Image
The Evil Within 2 will be revealed at Bethesda's E3 conference - Link
Call of Duty: Infinite Warfare will be revealed as PSVR compatible - Link
Shadow of Mordor 2 will be revealed at E3 - Link
Ape Escape 4 is in development at Sony Japan Studios - Link
Killzone 4 is in development at Sony Guerrilla Cambridge - Link
Knack 2 will be revealed at Sony's E3 conference - Link
Beyond Good & Evil 2 will be revealed as an exclusive at Nintendo's E3 conference - Link
A new Battletoads developed by Rare will be revealed at Microsoft's E3 conference - Link
A new Age of Empires will be revealed at Microsoft's E3 conference - Link
An exclusive 3rd party remake will be revealed at Microsoft's E3 conference - Link
An exclusive 3rd party JRPG possibly Project Kyoto from Mistwalker and Silicon Studio will be revealed at Microsoft's E3 conference - Link
Halo 5: Guardians will be revealed for PC - Link
Sunset Overdrive will be revealed for PC - Link

Resident Evil 7 being exclusive to PS4. Glad that didn't happen.

Battletoads (plz let this die)
Devil May Cry 5