fn main() {
    println!("Relevant to the article, I have a question to the Rust community as someone who doesn’t know the language.\n\nIs it a meme that you want to rewrite everything in Rust, 
or is it kinda actually serious?");
}

It's kinda serious, but definitely also a meme. Basically, Rust is the safest mainstream language out there (unlike languages like C or C++, which are full of foot guns, or things like JavaScript or Python, which aren't even strongly typed), so there's a strong desire to rewrite things in just because you often don't encounter stupid bugs in Rust code - the compiler won't let you write it. There are safer languages out there, but they're highly impractical for general purposes and are used for insanely mission critical shit (e.g. pacemakers).

I'd give this a quick watch: https://youtu.be/voRBS0r4EyI

Both. Primarily most software written in C should be rewritten to a memory safe language, be it Rust or some other alternative. Because there is a lot of software written in C, this is a veeeeery long term goal, and will probably never be achieved 100%, but at least Microsoft seems to be on board with this.