Due to ability to work without stdlib, Rust is system language in a sense Go never will be, to the point Go authors withdrawn this definition.

> Is Rust really a suitable replacement for Go?

It depends on your requirements for the ecosystem. If you need compatibility with Go or Go libraries, than it's not a replacement.

Libraries and support aside, any program written in Go can be written in Rust (and going back to nostdlib, many programs written in Rust cannot be written in Go). If you have required libraries, I'd say it can be written comparably quickly and easy. For example you can have web service returning hello world in 10 lines of code or so in either.

They are popular in different circles, but that is mostly not related to technical abilities. For 99% of of applications, you could pick either one.