The C language is the big elephant in the room. Everybody is writing C code but nobody is talking about. Let us change the rules of the game and try to overcome outdated C syntax and use a different kind of programming language for writing operating systems kernel, programming embedded applications, create graphics library and write object oriented applications.
Possible candidates for replacing C code are Java, C# and especially C++. A short look into a Linux distribution have shown that the C++ language isn't used very often https://dwheeler.com/sloc/redhat71-v1/redhat71sloc.1.00.html Only 15% were written in C++. And the assumption is high, that especially programcode which is not installed on real computers, for example KDE was written in C++, so that on running machines the ratio is worse for C++. But why exactly was C++ never able to replace C? The first version of C++ was published in the mid 1980s. Since then there was enough time to rewrite and recompile all the code. But this project was never started. All the newly written code is using the normal C language with minor modifications for example C99 instead of C89.
The paradox situation is, that C++ has replaced C in one category: the amount of books written about Object oriented programming in C++ is much higher than for C. The only book ever written about OOP in C was published in 1993 “Axel-Tobias Schreiner: Object-Oriented Programming With ANSI-C, 1993”. Apart from the book, there are two! (not more) Dr.Dobbs articles in the 1990s which are explaining how to program classes in C, and in some stackoverflow postings the topic is also discussed.
In contrast, the amount of papers, journals and books who are explaining how to program Object-oriented in the C++ language is larger than 20k overall. Additionally, nearly all university in the world is teaching how to program in C++ object oriented software. It seems, that the problem has to do with the difference between written code in the wild (mostly C) and computer classes in the university which are focussed on C++.
From a technical perspective it's not very complicated to create object oriented code in C. All what is needed are some function pointers, some structs and a bit discpline of the programmer. A look into existing software project at github will show, that most C programmers are experts for object oriented code. They are managing complexity in the written code by combining structs with functions in the same module. And they have no need for other programming languages like C++, Java or C#.
The only user group who is using dedicated OOP languages like Python or Java are newbies who are not familar with computer programming. They are reading all the C++ books in the hope to learn how to write object oriented code. This paradox situation can be overcome easily. What is needed are books with the title “OOP in C”. SImilar to to the mentioned book from AT Schreiner but published in the year 2020. Such books aren't available yet. And exactly of this reason, the newbies won't learn C at all. The typical newbie has understood that object oriented programming is a here to stay. Because it simplifies the programming of GUI Applications and games very well. And because the newbie has never programmed in any language at all, he decides for a typical OOP language in the hope this is the future. For example he is learning Java or C++.
The consequence is, that the newbie will waste his time. Because C++ won't never replace C code. The C language is way to powerful and provides too much object oriented features that expert programmer will switch to a different kind of language in the future. Basically spoken the existing software projects written in C for example the Linux kernel, the Windows kernel or a larger game can be translated with an UML generator into a nice looking object-oriented diagram. That means, there are objects (aka structs) and functions which have access to these objects. It's not possible to reprogram the Linux kernel in C++ because it is using object-orientation already.