The lens needs to be more firmly on "where do people do specific tasks more effectively". Look at productivity, efficiency and human metrics to determine which tasks are typically carried out better where (by individuals, teams and departments). Collaboration, celebration and community are three strong use cases for the office. The power of casual collision cannot be underestimated. Forcing people into using the office, like forcing them to use PowerPoint for everything they do, is futile. They will quickly realize it is not always fit for purpose and in some instances can hamper their deliverables.