> Ignores that there is already a well established C alternative: C++.

The key point is, C++ added numerous features to C, and at the time, it was the only language occupying that position (or perhaps Objective-C, too?).

Today, a successor to C cannot simply replicate what C++ did. Add too many features, and it will be viewed as a successor to C++ rather than to C (as is the case with Rust and D). Conversely, keep the additions minimal in order to stay close to C, and you end up in a "red ocean" crowded with Zig, Odin, C3, Hare, Jai, and others.