Most single C implementations have died out.

There is hardly any C compiler worth using that isn't equally a C++ compiler .

In fact, there is any C compiler left worth using that hasn't been rewriten into C++.

There seems to be at least 2 lcc forks (lcc-win32/win64, and pelles-c) that have their own small communities. Although maybe they are dead.

My current C compiler is implemented in D :-)

That may be true in your bubble, but I don't think this is true in general. There are still a lot C compilers out there, compared to 3 or 4 that do C++.