Fujitsu announced a finger gesture sensor. The concept look to me that of “Ring”. I suspect they will become a main stream device, because the finger ring on index finger doesn’t fit in everyday life. For example, it is difficult to wash your face with a finger ring.
In several months ago, Toshiba annouced Google glass like device. I suspect they will become a main stream device, because of the same reason. Google glass invites privacy concerns with people nearby.
Weareable devices should be hidden. They should not be an obstruction of life in any means.