Honestly I don't get why some people want to move to static types. Ruby is a dynamic language, that's the point of it... Giant orgs can just use Java or something. We need some languages to stay productive for those of us who work solo or in small groups. If I wanted static types I'd use Java, Go or something (probably Haskell).
Mostly, I really want Rails in a typed language.
I was writing a web app in Rust (I want to be cool!) and only after a couple hours of implementing CRUD did I realize I'd effectively made an inconsistently implemented rails scaffolding. The default opinionated round trip for DB -> application -> UI for CRUD is still really slick.