I completed the Medium research study recently, from their questions, it looks like they're attempting to hone in on a couple things; motivation and experience. Why are people writing on the site, what or who do they read, how are they interacting with the platform and those within it, etc. Here's the crazy part, I think the paid content model is the future of social and conventional media; if Medium decides to implode this site, it would be tragic, but possible. I love your urgency, better to be prepared than sorry.