I think/hope we're reaching a stage where start-ups use the language which is most appropriate for their field, or where they're able to attract the right talen

I think/hope we're reaching a stage where start-ups use the language which is most appropriate for their field, or where they're able to attract the right talent. If you're in finance, there's a good chance you're using Java, C++. If you're building a web-app, it's probably javascript/node, and likely moving to Typescript AI? I whole lot of python. So I'd take a look at what area you're interested in working in, and then make sure you're familiar with the language and tools which best fit that interest.