I believe we're hoping that Clang/C2 will satisfy those who want to build C99 TUs on Windows. Personally, I have absolutely no interest in C99 (I wasted a year and a half of my life learning C before C++).
Turbo Pascal -> C (meh) -> C++ (great back in business!)
Even though I mostly do JVM and .NET nowadays, still enjoy playing with C++ on the side, specially for mobile OS coding.
I see dropping C support on Windows as a means to force developers to migrate to more secure languages, but of course Microsoft should do what makes business sense.