My first thought is that you should add these graphics to one of your courses. It's a nice visual way to demonstrate what's going on.
Next, I simply could not get past trust. I kept thinking that the private company that holds your cryptotag provides insurance, which, of course, brings us back to some form of traditional banking.
I once tried a "brain" wallet that involved steganography. The code was an unforgettable number linked to a book that required a procedure to determine how to connect the aforementioned two to decipher the private key. It worked great, but after a few uses, it routinely took me an hour to figure out my own code. And even then, you still have to share it with someone else so it lives beyond a personal injury.
In summary, "I got nothin!"