I sometimes wonder if we as an industry should revisit XML for those use cases where painful JSON contortions are being used, now that LLM's can plausibly support writing the syntax for XML-adjacent languages like XSLT without as steep a learning and sustainment curve. My natural inclination is to design to accommodate as complex a space as the business requirements project for, because representation data structures and languages are so incredibly painful to change late in a product's maturity cycle.

So I've never rejected XML out of hand, but I've always been "show me" skeptical of calls for it and pushed for explanations on why the business requirements feel the justification to adopt XML. Sometimes I've seen it totally makes sense, but with the conceptual rigor it requires in those use cases, the skillset and expertise of the development team has to reach a higher than average bar. I'm cautiously hopeful LLM's might help with lowering that bar, but time will tell.