But before Palm Pilots, there was the Newton so loved by techies, just like Glass. So snap may end up the palm pilot or one of the dozen PDA knockoffs that were around (I seem to remember some Microsoft ones too). It seems like concepts float around in several iterations, or as many as it takes, until someone hits the sweet spot.

I'm not really knowledgeable about the "wearable" market, but to me it doesn't seem as ubiquitous as the smart phone.