@Bernd: It already exists and is called Qt.
Joking aside, you are correct. It would be quite possible to create a more up to date library in modern C++ that follows .Net design, but I guess it is not in Microsoft plans.
Since I haven't not seen it, I guess someone needs to again make the issue that Microsoft is the only C and C++ compiler vendor that does not implement any C99 features.
And regarding C++ I am really happy that Microsoft has realized that C++ still drives the world and many programmers use it every day.
Still it would be nice if C++ would get the same attention as the managed languages in Visual Studio.