Just as Steve Jobs camped out by the river and waited for economical capacitive touchscreen technology to come floating by, somebody somewhere is waiting for adaptive optics to become practical at the consumer level. At that point it'll become possible for AR glasses to begin to replace conventional eyeglasses for presbyopes and myopes, and that'll be the NBT.

Everybody working in the AR field now is starting too early. In 2003 the iPhone was impossible, while by 2007 it was inevitable.