1) For imports, the namespace hierarchy should have a one-to-one correspondence with the file and directory hierarchy.
2) For publishing code, instead of modules and Cargo, there would be one huge worldwide repository. You'd be able to freely import anything marked public, and the build system would cooperate with version control to make things work seamlessly.
Unfortunately it's probably too late for Rust to adopt such ideas. I wish some new language used them, though.