I quite like your idea of jumping across functions living independently rather than in files, and agree that a future AR approach for this is likely the way to go. I'd be very interested in something that's like the Minority Report interface, or even better, being able to visualize the code as being in a fully 3d space that I could navigate around (rather than having it come to me).
The git editor you showed looks neat, but I can't imagine myself using it. On a related note though, I quite liked the interface of the game TIS-100 and am wondering if there could be a professional version of that.
But zooming back out, I still can't seem to imagine programming as an activity being done entirely without text (or a pictorial equivalent), and would thus still argue that it is during this act of "translation" of pre-verbal neural activity to language that the program is created, perhaps especially because of how non-linear this process is.
P.S. What's the "no more than 7 rule"? I don't recall ever hearing of that, and can't seem to find any online sources. Is it about the 7±2 chunk limit on short-term memory?