> For example, in systems programming over that same timespan we've had assembly, c, c++ and rust.

I don't think you've picked a very good example here of a field where the lingua franca has progressed over time. C still dominates nearly all systems programming, against all odds. It dominates operating system development, driver development, embedded systems development, pretty much anything that demands an extremely high degree of efficiency.

I agree with your overall point regarding SQL and its superior stability, but C is an example of where popularity won out against many better options over time. It's not like Rust was the first mainstream attempt to create safer languages for systems development either. There's been many over the years designed to fill the same niche, with more modern features, tools and goals. For better or worse, C still dominates the landscape for reasons entirely independent of whether or not it was truly the best tool for the every task.

Also, I'd contend that your claim regarding the popularity of NoSQL is incorrect. If you only talk to web developers writing Javascript, you'd get the impression that NoSQL is taking over the world. But the reality is that amongst pretty much every other demographic, SQL is still highly regarded as the ideal technology.

>You still haven't explained why SQL in particular has ruled over its problem domain for over 40 years

Well yes, because I argued that it was irrelevant to the original question: can SQL be improved?

Additionally I actually did address the question of SQL’s stability, at least partially: it’s not SQL thats so stable, but the relational model. SQL just happened to be IBM’s, and IBM was highly successful pushing its DB around, and Oracle (kind-of) cloned it to push their DB around with less contention, and so it went on. But its the RDBMS engine that primarily pushes a DB’s value; The SQL language is a ride-along.

And once more to be clear: its longevity is not a result of SQL’s quality, but the quality of the relational model. Thus its popularity, and stability (its also not that stable, in that its heavily extended by everyone in arbitrary fashion), is irrelevant to the original question.

>SQL is not that popular, as the NOSQL movement

If people are trying to make use of NoSQL because they want to avoid the SQL language (not the relational model), they’ve made a grave mistake in understanding their technologies; I don’t think such a naive opinion should be considered relevant to the equation.

If they’ve chosen NoSQL to avoid the relational model, then their choice says nothing about the SQL language.

I think the historical truth is that Oracle was first to market, and IBM just adopted SQL so it would not risk being waaaaaaaaay too late to the market "party". [Darwen, "Why are there no relational DBMS's"]

> If people are trying to make use of NoSQL because they want to avoid the SQL language (not the relational model), they’ve made a grave mistake in understanding their technologies; I don’t think such a naive opinion should be considered relevant to the equation.

Yes, they are trying to avoid the relational model by avoiding SQL because SQL has basically been the face of the relational model for 40 years. if there was something better, they'd use that. Nothing better has come up, and i don't know why either.