Great questions! Thank you!
Well there is plenty to think about and first check whats already there.
Regarding Hive I guess the developement will be mostly in the second layer. While there will be economic sustainability the aim is not to profit but to influence (for good I hope) more like the wikipedia model.
Regarding teaching media I guess there will be text and video. Maybe even live onlines, but as I said the PoC must be well defined.
Regarding PoL proof of learning, thats a very interesting idea I admit I didn't much think of. The goal is to give free access, maybe proof of learning can be done via tests executed by another Dapp.
Coursera afaik is centralized organization for profit. While Coursera can be a distinguished member and still profit, it will have to give free access and change a bit its business model to gain by creating more content and maybe monitize by advertising online or private tutors, and less rely on paying subscribers.

Thanks for the questions and reading. Keep them coming :)