Waiting for Microsoft to make a compiler seems like it ought to be orthogonal to moving the language forward, especially when non-Microsoft tool chains are already doing better with that particular language.
Microsoft has enough on their plate bringing C# and .Net to Linux and Unix, and I'd much rather they get that right than compete with GCC and CLANG. (That and Docker for HyperV and Windows Server.)
Also, Visual Studio 2015 will ship with clang (http://blogs.msdn.com/b/vcblog/archive/2014/11/12/visual-stu...). Yes, that's for Android (and, in the future, iOS) only, but it would not surprise me if that it is a sign of things to come: either Microsoft starts following developments faster, or people will move to clang for development. And I doubt the current Microsoft would be bothered if their customers moved to use clang, as long as they kept using Microsoft technologies (even if that's limited to running on Azure)
Not really. It's one of the top handful of compilers and none of them are "original" wrt the language standard.