Personal educated guesses:
1. Microsoft will debut an all new "pro controller" for the Xbox One.
http://www.neowin.net/news/microsoft-is-working-on-a-hardcore-game-controller-for-the-xbox-one
2. David Cage's new game will show up in some capacity making up one third of Sony's notable first party announcements. Guerilla will be the second. Who knows what the third is.
3. There will be no Polyphony, Team ICO, or Kratos mentions.
3. Japanese developers/genres will have notable appearances at both conferences. Kamiya, Nomura, Trolljima?
4. People will realize that exclusive doesn't really mean exclusive. Sequels are always multiplatform if you don't own the I.P.
5. Microsoft will win Best E3 CONFERENCE. Phil will throw every single internally developed game onto a mega screen with a 5-10 minute gameplay demo. Halo, Forza, Rare, Scalebound, Crackdown 3, Quantum Break, etc. This will be the first MS conference that focuses a majority of it's efforts on first party tites.
6. Sony will be third party heavy, like a Microsoft Golden Era conference. People will ask - "Where are the exclusives?" Conference will be strong, excellent even- but will fall short to MS.
7. Giocorsi's segment will be the best Japanese announcements of E3. Lunar 2 Eternal Blue, Yakuza 0, and classic untranslated SNES JRPG's will find their way to Vita.
8. Sony's conference will end on the release/pricing announcement of Morpheus alongside a PS4 price drop to $299. Most people will call this anticlimatic because they wanted the Last Guardian or God of War.
9. Microsoft's conference will end on a cutscene of Black Tusk's Gears of War, most people will call this anticlimatic because they wanted in game footage.
10. The same Dolan "Everything was ____" meme will somehow find recirculation.
11. Adam Boyes will make an announcement that will break GAF.