On my area of work only Java and .NET get to play, and in what concerns UNIX like platforms most customers only care about Java.
The only one that is growing, although I rather not, is Go, as we now start to jump into the same container bandwagon as everyone else. And even there it isn't taking anything away from our Java/.NET setups, rather complements them.
What are good reasons to choose Go? If I need a language for non-scripting tasks, I would choose Ada, which is very easy to read, has a nice type system and generics, performance, and you could statically compile everything if you wanted.
I don't know anything about Ada, so perhaps that is a better choice!
But for my personal experience Go's concurrency features, type system, and simplicity is pretty great for getting up and going quickly with performant code.
Python is ideal as BASIC replacement and scripting language, for being a glue language for C and C++ libraries, almost any language can do that.
As for Go, when they adopt generics, until then I rather spend my productivity in Java and .NET land, and only deal with it in the context of containers eco-system.
This sounds very similar to the shop I'm in. Go isn't replacing any of our legacy Java stuff, but we have new tooling to supplement the legacy stuff built in Go.
The only one that is growing, although I rather not, is Go, as we now start to jump into the same container bandwagon as everyone else. And even there it isn't taking anything away from our Java/.NET setups, rather complements them.