Zawinski's Law, when taken literally, argues that programs all eventually need to be communicated with by people and other programs using a generic protocol and without using program-specific or domain-specific libraries to do so.

Unix shells (local), I'll add in HTTP (remote), and Email (remote and asynchronous) are the only forms that are ubiquitous, precisely because they enforce no structure for the payload. The structured alternatives are only popular in specific domains because they create their own ecosystem. As long as input can clearly be parsed, which goes hand in hand with being human-readable as long as you're not trying to be too efficient, you get schema implicitly transmitted out of band (by having output that you can visually inspect) and interoperability for anything that can read and write text.

I'd be interested in other directions this might go, but I remain skeptical of anything that will introduce and enforce a new paradigm that requires adding complexity to programs to accommodate it.