What about the development of videogames?
You can develop video games in any language out there. Heck, you can write it in JavaScript if you'll write a compiler for it. The key developing method in modern video games is accessing Video Hardware through series of interrupt calls via pure assembly. As long as you do that, you can lay any language on top of your hardware code.
Any modern operating system does not know what Class or an Object is.
Every code that is loaded in memory is represented as such: Text segment (that's what the C functions are), Stack (local variables in C), and the Heap (dynamic memory - whatever is allocated via malloc() and such). This program set-up can't get any more perfect for C (or any other procedual language - not C++, Java or C#).
In addition all core OS service libraries (Kernel32.dll or libc.so in Linux) were made to be used with C primarely. OpenGL API is also made primarily to be used with C. Qt, KDE, (and whatever the hell else written in C++) all lay on top of the X Windowing system which is a C language API. Even .NET stays on top of the Win32 API.
I can't wait till someone will write an OS Kernel in C++. (Please don't mention anything about the "Choices" operating system")