Lots of good feedback so far. My first thought was to analogize to gyms. In the United States, and maybe elsewhere, gyms fall into two camps. One hopes you'll sign up and never go, or if you do go, then you'll treat it more like a spa visit -- buying a massage, or a "healthy" smoothie -- so you're either free money or else profitable per visit. The other kind of gym keeps membership to a fixed number, and will actual…
Marketing would be absolutely crucial, as you and many people have rightly pointed out.