If you just use wiring instead of bluetooth, you don't have a latency problem. The upcoming Pebble Core supports wired audio-out and microphone. Just strap that on your head, like I've been doing with the iPod nano, and you can talk to it (IF the Pebble Core has Android with speech recognition and text to speech).
I'm not comfortable with a 3G radio a centimeter form to my brain, perhaps 2G (Edge) is less problematic in that regard. Make it water-tight and I can use echo location underwater for navigation
I've made a hearing aid app for iPhone, and I have people ask me all the time why I don't support bluetooth headsets.. That extra delay BT introduces makes the experience worse, but I suppose the technology is magic to most people.
It'll be interesting to see if the AirPods have similar latency issues or with push toward Bluetooth Apple have resolved many of the latency issues (obviously low latency wireless is totally possible).
I've a passionate relationship with wires, and often thinks of grabbing bluetooth earphones, do you think BT is also risky ? At least there are some BT modules that one can clip on a shirt and wire the headphone jack as usual, you're still wireless from the source.
I think eventually the mobile data radio is going to migrate out of these mini-tablet interfaces we call phones, and into either a wrist-watch or pocket-watch form factor, with local wireless accessories fleshing out the rest of the UX.
Rumours earlier this year said that they dropped plans to add a cellular radio into this year's watch due to battery concerns. Give it another year or two and they may solve it.
Then you could leave the house with nothing but a watch and wireless headphones and do various tasks from working out, listening to music, calling and messaging people, getting directions or booking an uber. No phone required.
I'm not comfortable with a 3G radio a centimeter form to my brain, perhaps 2G (Edge) is less problematic in that regard. Make it water-tight and I can use echo location underwater for navigation