You may think you deliver legal services or accounting services but what are your clients REALLY buying. There are lots of examples of industries that thought they were in one business and someone else came along, under their noses, and took the business away.
Disruptive technologies can change the game for businesses, creating entirely new products and services, as well as shifting pools of value between producers or from producers to consumers.
http://www.mckinsey.com/insights/business_technology/disruptive_technologies