A lot of people have already said it but I'm gonna say it again: Javascript. I think that we will be able to code everything in JS, in addition to its native language.

False.

Javascript is just the "controller" for the "host" program.

What your Js can do depends largely on the "host" program in which JS runs.

The "host" programs could be the web browser or nodejs, which are written in C/C++.

If the host program doesn't support it, JS can't do it. Try to do raw TCP in the browser, can you do it or you have to enable/ask the browser support for it?

Whenever you do something cool in Javascript, web socket, network or 3D rendering, remember there is a C/C++ programmer somewhere who did all the works for you.