One caveat I wonder about is how this kind of constant context switching combines with the need to think deeply (and defensively with non humans). My gut says I'd struggle at also being the brain at the end of the day instead of just the director/conductor.

I've actively paired with multiple people at once before because of a time crunch (and with a really solid team). It was, to this day, the most fun AND productive "I" have ever been and what you're pitching aligns somewhat with that. HOWEVER, the two people who were driving the keyboards were substantially better engineers than me (and faster thinkers) so the burden of "is this right" was not on me in the way it is when using LLMs.

I don't have any answers here - I see the vision you're pitching and it's a very very powerful one I hope is or becomes possible for me without it just becoming a way to burn out faster by being responsible for the deep understanding without the time to grok it.