I don't know if you are aware or not but your newsletters are serving as a guidepost for many writers here on this platform. At least those of us who take our partnership role pretty seriously. It's quite helpful. I suppose once a coach always a coach, right?
Furthermore, I think the person who suggested the audacious goal suggested it from a personal user driven perspective. Sometimes we think a platform works only the say we use it instead of the way it was designed to be used.
As such, one could miss that Medium doesn't need to dominate long form publishing. Why? Because Medium has the tools to serve as Top Choice but also as a link between how we use other platforms. If I choose to have a Substack newsletter--Guess what I don't have an audience. Guess what platform has a built-in audience--yep Medium.
If I have a wordpress blog, I don't have an audience or enough content to draw an audience. Guess what...okay, you get it. I can go on and on. I do think a Medium University is needed. It can clear up a lot of misconceptions. Sorry for writing a post here.