This might be a complex or long-term idea, but is it possible in the future for a host operating system and the Rust/Cargo toolchain to support fine-grained control over resource access at the level of individual libraries or modules?

For example, could we define boundaries so that specific libraries/modules are restricted in what resources they can access (like memory, files, or system calls), similar to how the Linux uses the MMU, or how embedded systems use an Memory Protection Unit?