Why would JS be less long-term-valuable? It's only 4 years younger than linux, it's more common than linux and has a much larger community (especially compared to the linux kernel driver one). I don't see either going anywhere in the next 20 years.
But, they did acknowledge it. And they're now making design decisions to facilitate the web as an application platform, rather than intentionally trying to make application development as difficult as possible to dissuade it. So now we've got WebAssembly and tomorrow or the day after we will have any language anyone wants to use being used. In that arena, Javascript will get pantsed and laughed out of the room. It will probably happen with pretty amazing speed, as there are legions of developers who have been holding their breath for this for 20 years.
In this discussion, when we talk about value, I think it makes sense to look at value in the sense of how valuable a skill is to the longevity of your career.
In that sense, JavaScript has some upsides - it's everywhere, and will likely continue to be everywhere. There will be lots of demand for JavaScript development.
But because JavaScript is everywhere, tons of people know it, and tons of people are learning it. So although there will be lots of demand for JS development, if you're a JS developer, there will also be a ton of people offering a skillset that is broadly similar to yours.
As you mentioned, the demand for something like Linux driver developers is tiny in comparison to the demand for JS developers. But the talent pool is relatively tiny, too. So it might be easier for you to differentiate yourself because when an employer is looking for someone with your skillset, they're not going to have to wade through hundreds of resumes from people who look pretty qualified.
In general, I think it's most valuable to specialize in solving a certain type of problem, where programming just happens to usually be the best way of solving it. It's often easier to sell yourself as a solver of specific kinds of problems than it is to sell yourself as a generalist with experience in JS, HTML, CSS, etc.
Given how much JS development thrashes, it's a pretty reasonable bet that whatever you're learning this year will be out of fashion next year, and irrelevant in five years. That's the high-order bit, when you're thinking about your career.
Even for something as "narrow" as linux kernel development, I can pretty much guarantee that someone will want hire you in 20 years, so long as you are competent. I can't make that guarantee for most technologies.
I really wish it were possible to make reference to JS in a less-than-glowing light without being downvoted, but alas. Substitute any other brand-new technology for "Javascript framework" if you're having difficulty seeing the argument.
But would I bet on Javascript over (for example) C? No way. Any new developer would be wise to learn C, even if they completely ignored Javascript. And I don't need any technical details about the language to make that call.