Can I suggest you find languages that solve problems you are facing?
Go is great if you do a lot of scripting or web dev. But wouldn't be so good if you're making chatbots.
A chatbot or real-time message passing would be great to use Elixir for.
Rust is great for WebAssembly or desktop programming as a replacement for C/C++.
Swift and Kotlin are the obvious choices for mobile development. Are your customers asking for mobile apps? Do you want to build mobile apps? These would be obvious choices.
Chase the problem you're trying to solve and use the right tool for the right job rather than trying to learn a language just for the sake of learning it. I find trying to learn a language I won't use to be something that quickly drops off my radar.
Q: What programming language should I learn next?
A: find languages that solve problems you are facing
Q: What language should I use to solve problem P?
A: Don't waste time on premature optimization, use whatever you are already familiar with and get your prototype done.
I also considered the 'Blub paradox' that Paul Graham talks about. I asked where the different programming languages fit on the "power continuum" - that is, its features, what's present and what's "missing", and how I should weigh each when thinking about that next language to learn.
Along with power, I like the view on utility.
As you write, thinking about your immediate problem and future problems (i.e., if you could anticipate) to solve, are also good points to consider when deciding about that next language to study.
Plus going for something that you feel solves a problem, or at least scratches a personal itch, makes it so much easier to actually go and learn/tinker/build.
Without that motivation, a lot of us struggle with going beyond various ineffective learning strategies (reading the docs, doing a hello world, getting sucked into the particular language's bike sheds).
Go is great if you do a lot of scripting or web dev. But wouldn't be so good if you're making chatbots.
A chatbot or real-time message passing would be great to use Elixir for.
Rust is great for WebAssembly or desktop programming as a replacement for C/C++.
Swift and Kotlin are the obvious choices for mobile development. Are your customers asking for mobile apps? Do you want to build mobile apps? These would be obvious choices.
Chase the problem you're trying to solve and use the right tool for the right job rather than trying to learn a language just for the sake of learning it. I find trying to learn a language I won't use to be something that quickly drops off my radar.