You're right that Python is not the native language for front-end of webpages (it's great for backend), or for Android or iOS, so you should something else.
Or, you can work on things that Python is good at. You don't really need to be able to write every type of code. It's acceptable, perhaps even good, to specialize.
- It helps to learn a bunch of languages, but not right at the start. Learning languages with different paradigms can help you write better Python (even though Python is pretty mixed-paradigm).
- Which language to learn depends on what you want to make or learn. If you want to learn new skills, go for something entirely different, like Rust or Haskell. If you want to build something specific, tell us what.
- Depends what you want to achieve.
- I like Python, Kotlin and Rust. I'm not yet confident enough about job opportunities in Rust. I'd rather work with Kotlin than Python, but I don't really want to do Android which is where most of the Kotlin jobs are... Maybe Python? In a few years when more companies adopt it, I'll probably choose Rust.
- Once they get big, they take long to die. It seems to go a bit faster for front end though. Python will probably be around for a while.
- Rust (not counting unfinished languages).