There is a monetization path, but not likely easy like selling direct to consumers. As others have commented - voice (and google glass!!) are useful when you don't have hands. For example, a dentist frequently needs to look at the computer screen or have the computer screen change a display while they are in the chair working on a patient. Making a command via voice seems useful (change to the next screen, etc) and/or also potentially showing some data in a heads up display. Another vertical could be hospital - being able to use a generic voice UI to turn on the lights and summon help seems useful.

Is the monetization path hard - yes. Trying to break into specific industries takes a ton of work. Additionally - you already have staff in these cases. Would a dentist get rid of her assistant for some voice commands? not likely. A hospital still needs nurses.