Agreed that Lightning-based headphones are not an automatic path to better sound quality, merely by dint of the connector. But analog headphones on the iPhone are currently limited by the quality of the DAC and amplifier circuitry that Apple chooses to include. With the signal presumably emerging as a digital stream (though nothing's stopping them from extending the proprietary Lightning standard, which uses on-the-fly reassignable pins, to include a new code that says, "these three wires will now contain analog stereo"), there is opportunity for companies to make headphones with substantially better DACs and amplifiers than what is included inside the iPhone (you could argue that they could do such already; I have a feeling the lack of an analog jack may put more of a spotlight on this). Whether anyone actually will remains to be seen.