Perhaps it would help if stdlibs were be versioned, with the chosen version declared in the project file. For existing languages, a lack of version would simply indicate the original stdlib, meaning nothing should break.

I definitely don't think stdlibs should be changed often, but it seems fairly damaging to a language when things may be added to a stdlib but never removed, no matter how broken or misconceived (see C++).

Rust is a great language, but the poor stdlib + overreliance on crates + explosion of unvetted transient dependencies makes it a hard sell for a lot of projects.