That has a catch 22. If you aren't going to start with Rust from the beginning, switching to it later becomes too costly and too difficult, which defeats the ar

That has a catch 22. If you aren't going to start with Rust from the beginning, switching to it later becomes too costly and too difficult, which defeats the argument of it being useful in general. Most often what's used in the beginning as "prototyping" is cemented into the system to the point that it's hard to change it. So yeah, better to deal with complexities in the beginning and save on switching later, than not to use it all.