Augmented reality won't be successful if the user has to wear a device on their head. When the day comes that a computerized system could be small enough to be integrated into contact lenses...only then will augmented reality take off.
I think it's tricky but not impossible to get people to want to wear a device on their head. (I mean widely, not just some people.)
Proof?
They already do: glasses, sun glasses.
Don't mistake what went down with Google Glass as an inevitable outcome. That was just a tech demo. I think the message got away from them (due in large part to their own actions), and many people started to get the impression it was supposed to be a real product. When it fell far short of that, there was a backlash. My point is, it doesn't have to happen like that.
Due to technology limitations, I think a smart device with a glasses form-factor is going to become widespread quite a bit sooner than something like a smart contact lens does.