Pricecut to $199 and PS3 ultra-slim (codename anorexia).

That would make Sony E3 winner.

But to be serious:

• MGS5 exclusive would be pretty epic. I consider Rising to be a spinoff series, as it has another sentence under the name: Lightning Bolt Action.
• Killzone 3 announcement is pretty obvious, I think.
• GT5 release date.
• Bungie game announcement on their stage. Remember what MS did with Rising and Rock Band last year even though they're multiplat?
• mass of 3D games/updates
• Killer Move games. Games that show Move isn't just a simple Wiimote clone. A Strategy game like Red Alert or Sumpreme Commander, which could be announced for PS3, would be perfect for the job.
• Project ICU, Sonys own Natal, to steal some thunder from MS: http://brightcove.newscientist.com/services/player/bcpid2227271001?bctid=48371815001