And JavaScripts staying power is backwards compatibility for billions of web pages, don't want to introduce another language to the browser because it would cost a lot of money for developers to build the engine and would increase the security attack surface, and all the browsers would have to add a new engine around the same time so developers would be willing to use it.

Sure, I don't disagree that Javascript also has some staying power.

But I suppose if you look at the web programming stack and its history (which helps explain how stupid and nonsensical it is) I'll bet that in the long run HTML and SQL stick around longer as a part, even when they're perhaps not very "good?"

As in, a good bit of the energy around Javascript is "dealing with its extreme shortcomings directly in a way that implies possible replacement?" Like, transpiling feels different from layering on top. And people transpile Javascript, but layer on top of HTML? Something like that.

And yet webassembly seems to be going somewhere.

It isn't replacing JavaScript. At the very least you still need JS to access the DOM. And, for backwards compatibility, I don't see JS going away during our lifetimes. And I don't see another language being added to browsers in place of JS (not including webassembly, which is not a replacement for JS).

XHTML looked like it would totally usurp HTML at one point but then we went back to HTML with avengence when everyone jumped on the HTML5 hype train.

Postgres used QUEL instead of SQL for the first decade of its life. There were several competing languages in the relational database space at one time, but SQL eventually won, no doubt thanks to Oracle and IBM's utter dominance in the space a few decades ago.

Declarative doesn't mean staying power. Reaching ubiquity through luck and random chance seems to be what achieves staying power. Javascript likely fits this category too. Browser developers 30 years from now will no doubt still be using Javascript.