The reason that D did not replace C++, IMO is garbage collection. D was so far ahead of C++98 that it wasn't funny, but garbage collection kept it from being a

The reason that D did not replace C++, IMO is garbage collection. D was so far ahead of C++98 that it wasn't funny, but garbage collection kept it from being able to be used in the same niche. D has gotten less dependent on garbage collection but C++11 (and then 17, 20, 26 (reflection)) have closed the gap enough that it is not the quantum leap that it once was.