Considering the fact that these are the de-facto UI languages for the World's most widely deployed platform (web browsers), do you think that javascript / html / css are going anywhere anytime soon?

1994 you: Considering the fact that these are the de-facto UI languages for the World's most widely deployed platform (Windows), do you think that the Win16 API is anywhere anytime soon?

While I see your point, you're comparing a closed-source proprietary platform to the web. Apples to oranges if you ask me

Even if Windows had been using X11/Tk or whatever back then, it wouldn't have made a difference.