Techcrunch had a relatively uninspiring piece on the future of the Apple Watch as enabled by watchOS2 which should allow the running of native apps. The piece touches on one interesting vector: taking vitals in rich ways through the API in order to monitor conditions. This is going to be huge. Not just because Apple will take care of distribution of the hardware but because developers will be able to leverage a common API for building all sorts of monitoring apps. And as the watch revs, there will only be more sensors to take advantage of.
Personally my short term interests are much more pedestrian is that I just want to be to have all of the media services I care about (Spotify for music, Overcast for podcasts & Audible for books on tape) to come out with apps that can pull the content from the Internet through the phone to the watch and intelligently manage a cache there. I worry a bit that the bluetooth headphone connection will be poor (it was during my one attempt at using it) but taking iTunes out of the sync equation feels like the first step to making the watch truly useful as a media consumption device.