There would have to be a certain kind of program that was easier to write in the new language than in most of the alternatives. Most of that would have nothing to do with the language itself, but with ``implementation details'': Can I read documentation at the REPL? Can I use a standardized tool to download and install libraries I need? Can I develop on Linux and deploy on Windows/Mac (or vice versa) without managing all the infrastructure by hand?
Most of this can be faked with C. Python does some of it better. Common Lisp tries, but you have to wrap your head around the package semantics before you can get anything done, and it's useless without Emacs and SLIME. Haskell is moving in this direction, but slowly; Go is outrunning it. D isn't even close. Rust is too young for it to matter right now but someday it will live or die on these questions.
If your language tackles these problems, someone will use it even if it's shit. If you make no effort, then it's a toy.