As for moving from Ruby to Rust or Go, Go is almost guaranteed to be faster for developers to learn. The reason for the complaints in the article is that Go is intentionally simple, and you're seeing many people migrating from dynamic languages to Go for those benefits. The fact that Go has its roots in C will make it immediately understandable to anyone with experience in a C-type language.
My final thought is going to address libraries and widespread acceptance. Regardless of your thoughts about Go as a language, there is no doubt it is here to stay. Underlying major technologies like Docker, it has already seen massive adoption. While initial signs are positive for Rust, you're still betting that it continues to build momentum and doesn't stagnate like Haskell.