This has been tried many times before, and eventually all these attempts die a lonely death. Why use extensions anyway? If one desired the luxury of modern scripting languages, switch to C++, Rust, Go or one of the other alternatives the article mentions.
Because regardless how some of us might dislike C and its security related issues, the truth is that no one is ever going to rewrite UNIX systems in other language, nor the embedded systems where even C++ has issues gaining market share.
So if one finally manages to get a safer C variant that finally wins the hearts of UNIX kernels and embedded devs, it is a win for all, even those that don't care about C on their daily work.
Until it happens, that lower layer all IoT devices and cloud machines will be kept in C, and not all of them will be getting security updates.
> So if one finally manages to get a safer C variant that finally wins the hearts of UNIX kernels and embedded devs
A safer variant wouldn't be C. What makes C great for OS development is that it is just a step above assembly and you as a developer are given tremendous amount of power to do good and evil. C#/Java are programming languages with training wheels and it's great for application development. But for low level coding required for OS, network stacks, databases, etc, you really have to take the training wheels off.
I suppose you can try and make the C type system more stringent, but then it wouldn't be C. And considering they are aiming for backwards compatibility with existing C and its immense code infrastructure, they will have to keep the "flaws" in c for all.
Time would be better spent making the libraries/kernel/etc sturdier but if they can pull it off and win the hearts and minds of OS developers, then so be it.
Also, people have been trying to sideline C for decades. Each attempt has only reinforced C's standing and reminded us why C is so essential for OS development. Anyone remember the ill-fated attempt by Sun with their JVM centered JavaOS?
The only way to make C safe without losing performance would be to accompany your C code with a formal proof that it avoids undefined behavior, and use a compiler which refuses to compile the code if the formal proof doesn't validate.
Which would be essentially impossible for any language like C.