Even some kind of auto model visualizer that helps every so often like a replacement for the ignoble package mmanager side panel view.
We're still so stuck on text editing.
I mean, the features you talk about are great-- but right now I can't even embed a little vector graphic explaining a function's flow in my source file. Every time I've suggested using a file format that allows things like fonts, styles, embedded images, to write my code, the reaction is always an insanely irrational knee-jerk against it. (Seriously, try it out with your programmer colleagues.)
(And to prod the bear a bit, a large part of the problem is the developers who insist in working in tools like the ones we're discussing here, designed in the '70s and using absolutely no technology that was invented after 1985 or so. Ludicrous. Imagine if any other industry worked that way!)
Then a couple days later, you found out they spent like an hour making ASCII art of some diagram because they couldn't just paste the actual diagram into the code. Sigh. Reason #3136269 I don't get along with other programmers.
I mean you're talking about advanced AI code that looks up Google links to explain code constructs, meanwhile 95% of the industry is using a code editor that doesn't even allow you to embed a link in a code file. (If you're lucky, it'll make an obvious URL clickable, that's about the best you get.)
Good argument?
What you're talking about is turning source code into a binary object. That's fine, if you use an editor that supports it, but you shun all other editors when you do that. There is a middleground that doesn't involve making your source code into rich text, imo.
As for "shunning other editors", well, frankly, why are we as an industry bending over backwards to support people using editors from the 1970s? Do you think Ford still builds cars with imperial measurements just so Old Bob the mechanic can keep using the tools he bought when he went into the field in 1968? No of course not, that's stupid. But that's exactly what our industry is doing.
RE editing text: whatever code object model one can imagine, it generally always serializes to text. I for one don't see the benefit of editing an abstract model in place of text. An example I liked was Fortress [1]. Fortress was a language that attempted to let users write code in mathematical notation using a special latex editor (iirc). It was found to be not a huge win, and they reverted to 'normal' syntax. This was one of Guy Steeles projects at sun.
So having said that, there are languages where editing the model is editing text: Lisp and Scheme.
[1] https://en.wikipedia.org/wiki/Fortress_(programming_language...