I don't really understand what #RustLang's Cell looks like at runtime. Does it still exist? Presumably it depends on T—something like: If T is on the heap, then Cell is a pointer, but if T is Copy then Cell is pretty much erased?

How is it not called a unihorn?

If you have an OSS project written in #C or #CPP, and people keep suggesting you add #Rust to the codebase, you should take that as a compliment, IMO. What they're saying is "I value this piece of software so much that I think it could be relevant for decades. I want to take steps to ensure the next generation of devs can keep this project alive." Deep down, this constant push to rewrite things in Rust is as much about fear of loss as it is about safety.