Good point on the battery life. One mitigation would be allowing quick (wireless?) charging from existing devices like smartphones, but there would still need t

Good point on the battery life. One mitigation would be allowing quick (wireless?) charging from existing devices like smartphones, but there would still need to be a minimally viable battery life. Example is the first Apple Watch that targeted a day's worth. I imagine system performance would be another early issue. Again in the example of first Apple Watch, it was nothing more than a display to render the paired iPhone's content. It wasn't until the 3rd generation that it became more standalone and able to function without a "co-device". Come to think of it in the case of the rumored Apple Glass, its rollout/development might be similar to that of the Watch. First couple of generations are heavily, if not entirely, dependent on the iPhone for data processing. But eventually it'll come into its own - thanks to the strength of Apple's custom silicon development.