Peter Kirn writing for Create Digital Media:

There are two common misunderstandings of the news. One reading (from Apple critics) assumes this locks you into proprietary Apple headphones. It doesn’t. The other (from Apple fans who don’t know that much about audio) assumes higher audio fidelity from “digital” headphones. It probably doesn’t mean that, either (there are some benefits to putting the digital-to-analog converters off the device, but no indication yet that will necessarily mean better sound). First, let’s consider why Apple would do such a thing.

I still don’t see the downside to making this change.