Eventually Glass-like products will take over smartphones. But just like desktop users like the additional power/speed of a larger device, there will be users that will still keep a secondary device tethered to Glass that will provide additional ability. Of course as fast WiFi becomes more ubiquitous this will become unnecessary as the work could be offloaded to "the cloud".
They are also working on a "for perverts only" version that will have limited X-ray vision - enough to see through clothes. Of course all the images, location and data will be immediately forwarded to the NSA servers for storage and the amusement of the reviewers. The porn industry is gonna sweat those glasses.