I'm disappointed about the lack of D, too, since the author gave Nim a try. And it's definitely more mature than, say, Pony (which is an interesting language for other reasons). Also, you can get excellent performance in D, really close to what you will get with C, and that's very often the crucial factor in systems programming.
I definitely consider D one since it's meant to be a continuation to C / C++ without caring about 'backwards compatibility' which is a good thing imho.
Also wondering if the author considered D.