What WILL happen:
-Apple announces a breakthrough device next Wednesday and showcases 16, 32, and 64 GB models all with an aluminum backing and glass-encased front plastic panel (white or black), they'll also say it is roughly as thin as the current generation iPod Touch and back it up with numbers. There will be a two-tone back, but only up top (black plastic area to allow for radio transmissions similar to iPad + 4G). Everyone will complain how ugly it is and then not even remember after they put their precious otter box case on it.
-Camera improvement: At least 9 MP, probably 10. Better auto-focus and optics.
-SOC is updated: A6 perhaps? And quad-core for sure. If not that, then at least quad-core graphics.
- <= 4" Display: There's no arguing this. It's a definite.
-Dock connector will in fact change to about 8-10 pins to accomodate new form and design. Go ahead, everyone: cry. They'll make adapters.
-4G standard: Across the board with all carriers.
-Much better Siri integration (yea remember her?): This will be announced out of beta stage and opened up to developers with new APIs.
-And of course, that "One More Thing" that Apple is notorious for: Something totally out of the ball park that sets this update apart from any other. LikeSiri was for the 4S. Apple will have to add that one thing that makes people go from "Eh, I can live with my current iPhone" to "Holy balls, I gotta have that!".
What WILL NOT happen:
-NFC communication: Not this soon, anyway.
-Taller form factor: It will become wider to fit the new screen, not taller.
-New headphones: Like I've said so far, unless they have to in order to accomodate the new design, this will not get an overhaul.
And cue the complaining...