I've been hearing about D for at least ten years. I don't think it's going to really break out at this point - it's been sort of lapped in the trendy, new language corner by Go and Rust and whatnot.
Worse, it's been lapped into the 'who cares' corner. D had a burst of buzz for a while, about 10 years ago, but at the time nobody really wanted alternative systems languages. IT got a little support, but mostly people ignored it. Now, you have Go/Rust/Nim jumping into the space and getting lots of Buzz, but if D is mentioned then one of two things will happen:
A) "Oh yeah, that language from the mid 2000s. I didn't want to use it then, why would I use it now?" B) "D? Oh it's from the mid 2000's? I wonder why nobody used it? It probably sucks."
Even if those statements are false, it's hit the same problem that a 50-year old programmer in the job market is going to hit, age discrimination.
Breaking compatibility with C isn't such a bad thing. Also I think C, C++ and D are easily made compatible with each other (I would not bet on that too much though).