It was always pretty clear imo that this was part of the thinking behind WinRT. Remember, Microsoft created Windows Media Center Markup Language (MCML) because .NET/XAML wasn't going to cut it in terms of performance. .NET was also originally in plans to be used as the Windows API and as a replacement for Win32 back in Longhorn but that was nixed for the same reason. Microsoft has been looking for ways to take some basic concepts from .NET and turn it into a performant API replacement for some time now.
Anyone who's read the WinRT language reference on msdn knows the emphasis they're putting on C++/CX.