Astute comments in this thread, that would resonate with several of my friends who are professional photographers or GA pilots. My interest in providing commercial services grew out of many hours of assembling and testing remote-control multi-rotor aircraft, followed by learning how to apply robotic systems technologies. I wanted to learn more about how these aircraft can be "controlled" by an operator/remote-pilot in real-time, but more importantly how to see the aircraft as a programmable flying machine of varying capabilities (camera/sensor/payload types and weights, flight durations, flight path accuracy, airspace positioning repeatability). All things considered, I was prepared to trust the equipment more than myself after a launch, at least part of the time in the field at a job site. As you might imagine, sometimes my trust level was tested... while coping with the rapidity of software changes from manufacturers or software developers.
Great, so what are they (UAVs, "drones", UASs) good for, and who would pay for Service 'X', if I invested in developing and offering that service, enabled by some configuration of equipment? Not being a Professional Photographer, Videographer, Licensed Surveyor, or (house/building) Architect, I spent 2016-17 doing low-income experiments, literally in the field but more so in the office, with or without input from various professionals. This range of experiences led to a greater appreciation of equipment
other than the aircraft itself, and especially the integration of software in ground-located equipment with firmware in the aerial vehicle. Eventually, FAA website authors acknowledged this perspective in
this FAA definition of a UAS, which positions the UAV as a component of a larger scope system called a UAS. Of course not every source agrees with those terms and definitions (not even on at least one other FAA webpage). And programming of attractive or informative aerial shots for various clients/customers is not a focus of FAA interest. Neither is low-altitude flights using PPK or RTK techniques for photogrammetry to produce accurate 3D models that various professionals would value.
So here's some observations so far, from one viewpoint. In some ways, one can say that a specific Service that applies a UAV/drone to a real-world problem/challenge/opportunity is like another tool in a current Professional's toolbox, and the full potential for the tool may be constrained by permitted professional norms/practice, human abilities, or lack of imagination/vision. In another way, a Service can be developed something like as in "Field of Dreams" (If you develop something new, appealing and affordable, they will come). That said, sometimes "the market" for a given Service simply isn't there now, and may never develop to be anything close to a primary activity that generates substantial income. Continual outreach with examples is probably key (if you can get in the door, so to speak). One's current equipment, particularly the software, may limit what you can offer with a high degree of safety and responsibility. One's operating location can also limit the scope of services and actual markets served, unless you are prepared to travel more or compete more vigorously with the aerial alternatives available to the client/customer/consumer. Most current demand that I see is for video clips with minimal, quick editing and maybe some discrete text annotations. I would
prefer to be doing more 3D Site Modeling for environmental monitoring projects or supporting higher-end property development, however I'm not counting on those activities to consistently generate income through a year. Time will tell. Certainly heard a lot of overly-optimistic predictions from product/service marketers, friends, acquaintances - and myself - about future business activity.