I just want to get my iPhone 7 prediction on the record:
Apple will remove the 3.5 mm audio port, but will not remove the DAC for headphones. Instead, Apple will pass the analog audio output to the lightning port, using four contacts on sides of the port. Two will be on the sides (let's say for the right and left channels), and will double as the contacts that hold the lightning connector in place. A headphone adapter would have two corresponding contacts on the side of the connector. Two more connectors will be at the rear of the port. These would function as the microphone channel, and a single corresponding contact would be on the connector. The phone would recognize the orientation of the adapter based on which of the two contacts on the port makes contact.
Port
__0____0__
|..............|
0.............0
|..............|
Connector/Adapter
_____0__
|...........|
0..........0
|...........|
Adapters for old headphones would be trivial to make, as they would simply pass each contact to the corresponding channels on the 3.5mm port through a basic connection. I would imagine that third party accessory makers could make these available for a couple bucks.
Apple will remove the 3.5 mm audio port, but will not remove the DAC for headphones. Instead, Apple will pass the analog audio output to the lightning port, using four contacts on sides of the port. Two will be on the sides (let's say for the right and left channels), and will double as the contacts that hold the lightning connector in place. A headphone adapter would have two corresponding contacts on the side of the connector. Two more connectors will be at the rear of the port. These would function as the microphone channel, and a single corresponding contact would be on the connector. The phone would recognize the orientation of the adapter based on which of the two contacts on the port makes contact.
Port
__0____0__
|..............|
0.............0
|..............|
Connector/Adapter
_____0__
|...........|
0..........0
|...........|
Adapters for old headphones would be trivial to make, as they would simply pass each contact to the corresponding channels on the 3.5mm port through a basic connection. I would imagine that third party accessory makers could make these available for a couple bucks.