It is nice to see Microsoft noticing that C++ still plays a major role in today's computing, but for me it still fails short.
The adherence to standard seems to be only to the features that Microsoft needs to write certain types of libraries, not with the language itself. Would have you improved your support if it wasn't for the new driving factors that are making C++ relevant again?
As for C99, it feels like an excuse. You mentioned gcc, but the truth is that Microsoft is the only vendor that supports 0 features from C99:
So all existing vendors are able at least to support give partiall support except for Microsoft.
For me this sounds like a political agenda, focusing only on .Net with "just enough" support to the rest of us.
And now you expect us to shell out again more than thousand euros to a vNext release to get back features that were already there to begin with?!