“Does gesture control really have a place in digital signage, or is it a flash-in-the-pan trend?”
Gesture control has been fairly difficult for years and seems more like a gimmick in most implementations. Many people are self-conscious, and trying to interact through motion feels uncomfortable and forced. While there have been many improvements over the years, this seems to be better reserved for specific interactions for gaming and certain experiential displays, but I doubt if you’ll see it mainstream. It would require more commonality in the interfaces as well as make its way into the home (much like voice control has) before it could be widely adopted.