I'm not very convinced by a language for improving python that have mandatory manual management of memory. I think the best bet for a "new" language to have success is to be the glue between the big ecosystems (C, C++, python, javascript, maybe also java, C# and rust).
This language must be much faster than high level language and easier than low level languages but even more important to be easily interoperable with the big ecosystems. Nim is well placed there, it satisfies the criteria of easiness and good performances, and has probably the better system for interoperability with the C and Javascript backend. However the interoperability story is still too weak and I think focusing more on it could be the way to success for nim. I don't know if it's possible (probably not) but the killer feature would be to be much more easier to do language 1 => Nim => language 2 than to do Language 1 => Language 2, where language 1 and 2 are at minimum C, C++, python and javascript And while the REPL is nice for data exploration or code experiment, I think a good development experience (IDE support, debugging) and even more a good deployment experience is much more important right now.
