I greatly appreciate your goal of building an objective portrait of the true state of the modern media marketplace; and I greatly applaud and agree with your comments about Michael E. Porter.
We are using Porter's ideas and five forces framework to objectively build a portrait of the global economy. We have been doing research for six years. Building a new industry taxonomy at the right level to perform a Porter analysis was our first step because we believe SIC and NAICS codes were not developed by students of Michael Porter.
Given your excellent description of Porter, why not leverage Porter’s industry analysis in your work? For example, maybe you should start with identifying the list of media industries in 1970 versus now? If you did that, I believe all your other work will be built upon a rock-solid foundation.
Again, great work; and I look forward to reading more about your project.