fwiw, though, there are digital audio outs on the market and have been for quite a while - they were out first, even. there was the spdif, for example. i have a still functioning sound card from the 90s with an spdif in/out. but, they didn't catch on...

a part of the reason is connectivity, right. the computer was never going to be the center of the sound system - more of an auxiliary in. so, you want the outs to conform to audio industry standards. meaning, you're converting everything to analog at some point. and,

that's kind of the crux of it, right. the complexity in the system is in the conversion to analog. no speaker can take a digital signal; that does not make sense. so, your headphones need to either accept a converted signal or convert the signal themselves. video doesn't really work that way. and, of course, strict data transfer doesn't need to do this kind of conversion at all.

so, there's not any benefit in changing the interface because you really can't increase the data speed on an audio signal. the only way it makes any sense is to put the dacs in the phones. but, that doesn't make any logistical or financial sense.

at the end of the day, the real reason that apple may be doing this may be to force you to buy an ipod and an iphone, rather than just an iphone. it's simply not a comparable technical leap.