> that a language that would be able to replace C, needs to target both the speed issue without compromise AND the efficiency of writing code,

C++ tried this. You can use null-terminated char arrests like in C, or you can use std::string and it works like Python or Ruby. C++'s problem is that by having so many features to please everyone, the interactions between some of the features are less than obvious, and there's always some feature you're encountering for the first time.