There's plenty of possible problems, but I think Microsoft regards it as a nice way to keep developers developing using their tools, similar to how Adobe takes a pretty hands off approach on piracy of Photoshop.
Pretty much, always a bit puzzled when people assume that Microsoft will throw the toys out of the pram at some stage. It's a net benefit for them if more people are using the language, rather than shifting to C or C++ and sticking with that instead.
