Lots of ideas above, rather speculative.
Overall, the claim above, as written, is a rather generalized prediction, not an inevitability.
Enterprise buying power and expectations create various pressures, sure. But there are other pressures and factors that need to be accounted for such as demands from other types of customers and the company’s expertise with what has worked well so far (simpler is better, compared to Jira).
Entropy is a law of physics, sure, but the ways and degrees to which it manifests in software is far from obvious or inevitable.
We live in a world of possible future scenarios, not of narrative-based certainties.
I predict GitHub Issues will remain considerably simpler than Jira for the next five years at least. As code analysis tools improve (traditional static analysis as well as LLM-based), I think we will see a lot of experimentation in this space.