The things you're describing are EERILY similar to some stuff I've been conceptualizing and thinking about recently, as inspired by the VPRI people's work/OMeta/Shen. I'd just remark that...

"The program is a UI, and UI interaction is programming. Unison panels take the idea of spreadsheets, which blur the distinction between UI interaction and programming, to its logical conclusion."

...this blurring between programming and interaction (which I've also thought of) probably offers a potentially viable path to much more powerful voice control of devices, since programming APIs serving as user interfaces can now also (besides graphical UI) implicitly define strict grammars for structured voice input. That's the one thing I thought of that I didn't see mentioned there.