Things I can realistically expect:
(note: this doesn't mean to expect all of them, but they all have good chances, I think)
- New Falcom title (in December, Falcom confirmed it's developing a PS4 game)
- Disgaea 5 (In July, NIS said it would announce the next Disgaea this fall, and before that in February, it said it would announce a PS4 game at TGS)
- Yakuza Next (it's being announced next week, but it'll likely show)
- Senran Kagura: Estival Versus (it's confirmed PS multi-format and Takaki has said he wants to make a PS4 game)
- Bloodborne (already confirmed, of course)
- At least one new SCE Japan Studio project
- News about Bandai Namco projects (Gundam, Idolmaster)
- News about D3 Publisher projects (EDF, Onechanbara Z2)
- Something from Acquire / Spike Chunsoft / Koei Tecmo (read below for possibility)
- That CyberConnect2 large-scale project to be announced soon
Things I think will happen eventually, but am not sure if we'll see it on September 1:
- Deep Down beta news (maybe, because an update on this is supposedly coming this month)
- Yoshinori Ono's second PS4 project (we already know he's making it)
- Team Ninja's first PS4 project (in February, they said they were making one)
- Gust's first PS4 project (never said they were making one, but with Atelier Shallie out, I'd imagine that's where they're going next - they jumped to PS3 pretty early)
- Persona 5 full reveal - PS3/4 multiplatform
Things I'd like to happen, but who the heck really knows:
- A new SCE Japan x Level-5 RPG
- Dragon Quest XI (it's in development, console unknown)
- Final Fantasy XV update
- Kingdom Hearts III update
It's sad that the last two things there are merely "updates," heh.