Will there be a 5+ inch iPhone? Will the iPhone get even bigger?
Will the iPhone get even cheaper?
This could go either way. Last year we expected a cheap, bargain-basement iPhone for the prepaid market and instead we got the iPhone 4 for free on contract on two US carriers, with price discounts intenationally. This treated them well last year, so I see no reason for that to change this year.
The safe prediction would be to guess that the iPhone 4 will disappear by the end of 2013, the iPhone 4S will become their "free" phone (making the number of carriers with a free-on-contract iPhone in the US three) the iPhone 5 will drop to $99 (on 4 carriers, now) and the new iteration of the iPhone taking top-dollar at $199, as usual, as always.
Will the iPhone be available in 128GB capacity?
I can't predict one way or the other on this. I bet it'll come down to how well the 128GB iPad is selling, but those numbers will never be public, so we'll never know. The conclusive evidence that it has sold well will be the introduction of a 128GB iPhone.
I don't think Apple is under any pressure to do so, as 16GB is still the introductory storage level for most smartphones, with 32GB being its only competition. The last time minimum storage jumped was when it went from 4 to 8 with the original iPhone, and it's stayed at 8 for the 3GS and now the iPhone 4. I could concievably see the free iPhone staying at 16GB instead of 8GB, but i don't see that change going across the board.
Will it have NFC? WIll it be beaming shit back and forth with something or other? HDMI-out?
No. Anyone speculating this nonsense hasn't been following Apple long at all, or if they have, has been deliberately ignoring behaviors inconvenient to their personal view. Apple does not like features that depend upon integration with other companies products, or interface with other organized bodies of technology. That was what inspired Passbook: every other company was banking on store's ability to install NFC hardware for their phones to play with, but Apple's decision was to use inexpenive hardware companies already had installed, to work with standard-issue QR/Aztec and PDF417 tags (the stuff bonus-cards and keyring tags use). (That's why Passbook tickets are coming to 13 stadiums this year and Samsung's CEO noted that "the use of NFC services is very low. Consumers... they don't even know how to use it.").
That explains AirPlay, instead of DLNA. That explains FaceTime, instead of Skype or some other 3rd party video service, and that explains iMessage instead of chat integration in the Messages app with another service. Apple owns everything they work with, and we can count on Apple owning the entire chain, and not using a technology if they can't. If they do introduce some new service, expect them to own the whole stack.
So, what is going to happen?
As far as the next iPhone, here's how I think it's going to go down.
Global, universal LTE.
If there's anything Apple hates, it's making multiple versions of the same thing for different reasons. They like making one thing and giving it to everyone: it straightens the supply line and allows them to include all shipments internationally when calculating component buys. They had to divide the iPhone 4 for compatibility with CDMA networks, so they reunified it with the iPhone 4S, a global, multicarrier iPhone.
The iPhone 5 had to be divided again out of necessity, as LTE standards worldwide were in flux at the time of its release, and companies like Qualcomm hadn't unified their antenna architecture. The LTE version of Gobi (a single chip that works on all versions of LTE) should exist by the next iPhone's release, so I bet the new iPhone will be one device to rule them all - one phone, global LTE. They'll market this either as "global" or "more advanced LTE coverage".
No design changes.
It's going to look exactly the same as the iPhone 5, and everyone knows in their heart that that's true. From 3G to 3GS, from 4 to 4S, that's what they do: redesign, and then amplify: they exhaust all the functional potential that that design has to offer before reiterating. Not a bad thing, considering it's the best selling phone in the world and looks fantastic. If anything, I guess some coating on the back to prevent scuffs might come up, but I think that might conflict witht the feel of the metal in your hands, so I wouldn't be surprised if its a spot-on duplication of form.
No surprise here, either. Whether they go to 10 or 12 MP is up in the air, but this will be the first double-digit-megapixel iPhone. Their camera size has been accelerating slower than the market because they custom-order their camera optics, but now's the time they make a competitive jump forward - it's just too standard a spec to compete on.
A faster, quad-core A7 SOC.
I don't think this is really up for debate: it's going to be called A7, it's going to have faster graphics and four cores, and it's going to be fabbed by TSMC instead of Samsung.
Longer battery life.
This is going to be the result of a combination of better LTE antennas, better processor and new battery tech, combined for an extra two hours of battery life. They leveraged the dual core chip for the 4S and 5 to power hardware accellerated graphice in the UI, but i don't think they'll do the same for the quad core as it will provide a negligable boost, whereas conserving battery life is the high-order-bit for mobile devices and LTE still weighs heavy on all-day use, no matter how much the iPhone 5 compensates.
I'll go into this more in a full iOS section, but suffice it to say that this is going to launch with it, with the OS being available for download on other devices the Wednesday before a Friday launch.
In short, it's going to be an "S" style update. iPhone 5S: twice as fast, iOS 7, better battery life, better camera, more carriers, same price. Not a hard sell, if you ask me.