Apple is sent out “See you on the 7th” invitations to the press, which has been widely interpreted to mean that that this is the day new iPhones will be announced. I interpret “See you on the 7th” to be a reference to the additional camera that is rumored to be on the new iPhone.
The main thing people have been already been complaining about is that the new iPhone will likely not have a standard headphone jack. I can think of a couple of reasons that they would remove this. I’ll preface this by saying that they wouldn’t just randomly remove something like that unless they felt the benefits outweigh all that complaints they’ll likely have.
The headphone jack takes (relatively speaking) a lot of room in the phone. There are a number of things that they could do with this extra room. The first thing that comes to mind is extra battery space, which translates to more battery life.
Second, along with a second camera, it’s likely that the new iPhone will have a second microphone. This could be leveraged in a couple of different ways. Noise reduction is one. Another is greater fidelity for doing speech recognition. Apple has already said that additional microphones would be of benefit to Siri and this could be applied to speech recognition in general, especially for “simple” dictation of notes and reminders.