"As you move up the sophistication spectrum, developers begin to experience "cognitive dissonance" when considering how much their time is really worth."
I am pretty sure that one of the reasons why cloud IDEs have struggled is that plenty of professional developers consider that learning an IDE or editor is a time investment that pays returns over a long period of time. On the extreme end of the scale, I still get near-daily use from the Vim knowledge that I picked up well over a decade ago. Investing personal time learning a cloud IDE may not be such a good investment, because those skills can be invalidated at any time.
There's definitely a lot of potential innovation that can be done in developer collaboration and environment setup, but I don't think that a proprietary system will get the widespread adoption needed to move the industry forward.