Apple is killing the headphone jack
businessinsider.com
businessinsider.com
The iPod touch is thinner than the 6/6S and it still has a headphone jack. Maybe Apple will remove it someday but there is no evidence that it will happen with the iPhone 7.
I assume they'd just use Bluetooth so most Bluetooth headphones would be compatible assuming they're to spec.
And 5mm is the absolute minimum thickness for a 5-inch device; you really don't want a slab-shaped phone that is any thinner, otherwise the structural stress on it will genuinely make it warp/bend/crack in people's pockets.
I haven't had great luck with Bluetooth devices connecting reliably, every time, and at any rate, with the shitty batteries that device manufacturers use, I expect that I will be bricking more than one set of headphones very quickly, if I even bother buying them.
The least expensive USB set I've found in the past has run around $30, and you get what you pay for. Good enough for highly compressed voice communication, but terrible at rendering music.
It's strange to me that some of the rumors try to spin this as a "cost savings" on the hardware in the phone. Removing the headphone jack wouldn't let them drop the DAC nor the set of amplifier circuits the speakers use because in order to be a "phone" it's presumed that it will still need speakers on the "phone".
Presuming that Apple continues to bundle in some form of earbuds with the iPhone after dropping the headphones jack it's essentially a net increase in DACs in the package (as I assume the speakers and headphone jack share a DAC currently; but I've not double checked an actual hardware breakdown). Quite the backwards direction for something rumors seem to be trying to spin as a "cost saving" measure.
Maybe it's all a conspiracy by Big DAC? ;)
[Bonus punchline: Big DAC is the name of the old school hip hop cover band I sponsor.]
The article also talks about how, but doing this Apple opens the door for more cost to own an apple by buying accessories to continue to use your existing headphones.
This article doesn't go into DRM when there is no digital to analog conversion. The killing of the headphone jack seems to open the door for the phone to decide whether its going to play the music returning to the original ipod problem of whether it was bought with Itunes or not.
There is always digital to analog conversion, it'll just happen upstream from the phone. There will always be iPhone -> headphone jack adapters.
My experience with USB in general is it's a PITA if you need to insert / remove on regular basis. The sharp edges scratch at the plastic, and you typically always try to insert it at the wrong angle first try, and so need to play the USB dance of switching back and forth until it finds its way in. Its impossible to do while in your pocket, which is where the jack really comes into its own.
I don't think as a connector it has the polish of the lightning adapter, but I also don't think it would be a disaster if Apple switched to using it.