To prove how hard it is to replace C, even Microsoft with its security speech and "we don't need C on Windows" has given up to market pressure.
The Azure Sphere device whose marketing message is all about secure IoT, uses C as its only language, despite endless requests for C++, Rust, C# support.
The new MSVC version will support C11 and C17, minus the C99 features that became optional in C11.
Language evangelism without market understanding doesn't go far.
C might not be perfect but it's clearly perfectly possible to write stable and secure programs in them.
1. Not all software is exposed to internets, or requires many 9-s in reliability like avionics. A videogame that crashes their hardware-virtualized compartment on 1 out of 100k consoles is not OK, but might be good enough in practice if the unlucky users are refunded.
2. We have higher-level languages which solve these vulnerabilities for acceptable performance cost, and even easier to learn than C.