Of the 3, javascript is the most dispensable, there's nothing stopping us writing platforms which have UIs designed in HTML/CSS but have a DOM controlled by python/c#/ruby.
I was not suggesting we stop progressing, but we need to recognise the phenomenal amount of overhead involved in replacing these 3 technologies. What benefit would be served when they can just be abstracted on top of, at least with regards to the web?
Case in point, Assembly Language, we could theoretically replace the standards that have been reached over decades of collaboration with something more suited to our modern leanings. But what would be the point, when we've long since abstracted it out of our minds?