Rust is lovely for security-sensitive code - I'm writing a customer identity management system with Rust+Postgres+Redis.

Go is... acceptable... for "glue" code where PHP would've been used a decade ago and Perl before that - all the successes of it I've seen fall into that sort of pattern.

Elixir is great when you need to think about networked, stateful systems on the scale of a rack of machines - it provides many of the components to help you design systems at that scale.

So... as ever, they all do quite seriously different things. I don't think many people need to build the sorts of systems Elixir is good for - it'll always have its niche in large-scale communications systems, though. A good many webapps fall into the patterns that Go is good for - take user input, munge it, send it to some backend system. A fair bit of code that drives the foundations of what those webapps are built on will eventually be written in Rust.