IMHO, Ruby is still one of tthe strongest language in term of ease of use, object orienteness and features. Go and Rust compared to Ruby will adress not performance but core scability and this can be addressed in numerous ways in every architecture.
I agree that you can address the scalability problem in every architecture in different ways. In ruby you'll typically have a mix of vertical and horizontal scaling that often results in a significant consumption of memory. This even though feasible comes at a higher price on cloud resources. I have experience this first hand and I think it's similar (at much minor scale of of course) to what companies like Shopify have experienced as motivations to change to something like Go.