Video and ambient mic would be nice, and data. We could have had this 10+ years ago, although it really only became practical with 3G I think.

Yeah something like the Pebble watch but as a Bluetooth-style headset. (Come on Kickstarter community)

It should support something more reliable than SCO and an input touchpad like Glass. It would also make sense to have some of the initial NLP processing in the device, or even a full ARM processor like the Glass running arbitrary applications.

You would be able to make calls through an offloaded cell phone using a more advanced profile than SCO HS.

If I could remove the device and place it on the car visor to use as a noise-cancelling speakerphone like the Motorola Bluetooth unit I have, even better.