Companies should be able to host their own environments and use cloud for development. IDX is perfect for that. Companies, in turn, don't have to provide powerful laptops to developers and use multiple mechanisms to keep the code safe from employee theft. Instead, all code resides on cloud on the company owned instance of IDX and users can work from much more inexpensive chromebooks.
Realtime collaboration features and direct link to gsuite platform to start audio and video calls to discuss code with colleagues would be cool.
Support for self-customizable virtual machines to keep the RUN environment different from BUILD environment would be great as well. Docker integration in the build env would be helpful as well.