C++ (or any C-Style language) developers would try out and adopt Nim if it read familiar.
We tend to forget that developers real job is not to learn a new language, but find solutions for problems and challenges. All what C-style developers want from a new language is to write and read familiar, if a C-style programmer can write a program in Nim after 30 min of reading the documentation and feels at home, they would adopt the language (Go, Rust). You can't force a redundant technology at people unless it provide something unique, you can't write something in Nim that you can't write with another language, what is unique about Nim is the cleaner, easier and modern programming style it provides, not its syntax, if Nim basically change it's syntax to C tomorrow, it will dominate in a year span. Look at the dominant languages, most of them are C-style, languages like C, C++, Java, Javascript, Go, Rust, Swift, etc, developers feel comfortable moving from one to another, it's easier for them to write/read logic in them. I'm sure I will offend a lot of people when I say that depending on Python programmers to make Nim popular is a mistake, and I apologize, I don't mean to offend, Python is popular among data scientist and ML prototyping, and those are currently in their comfort zone, why would they switch? if they switch, Julia is there for them. You want the C++ frustrated developer who want a powerful alternative to write systems, games and embedded. Those who think that Nim is a tiny toy programming language, I don't think they have been following language development in the past 10 years, so wait until Nim becomes the next "Shiny" thing and they will be the Nim experts who post "Hello, World!" youtube on how to become 6 figures developer in 15 minutes. The funny/sad part is that Nim has a lot to provide to overcome languages like Go, Rust, C++, C#, Java, Dart, Javascript (even Julia), yet it choose to compete with Python.