I've done my research and here's what I got in terms of potential reveals:
First-Party:
- Arrowhead's New TPS Multiplayer IP
- Secret Game #1 (Silent Hill)
- Secret Game #2 (???) - could be RaySpace?
Regarding those "secret games" from above, one of the individuals behind the Silent Hill leaks mentioned that there were two games that Sony really wanted to announce before information slip out about them - one of them being the Silent Hill soft-reboot in the works at Japan Studio - but ended up delaying both reveals from the june event.
Third-Party:
- Call of Duty: Black Ops Cold War - I mean, it has been getting leaked for several weeks now and the COD IP is strongly tied to PlayStation these days. I wouldn't be surprised if it was moved from the june event due to the game being behind schedule - everybody remember that this year's COD has had a rocky development.
- Final Fantasy XVI - I recently got confirmation that this game was not mistaken with Project Athia back in june and that an announcement should be on the horizon. Square Enix mentioned that they would unveil the games they had planned to show at their E3 press conference during june, july and august, so this could be one of their august reveals.
Wild Card:
Dead Space writer's new game - pulled off from the june event at the last minute. Could be it's own thing or one of the games mentioned above.