According to Naysawn Naderi, VSTS PM for Developer Oriented Testing, "the majority of the unit testing features of Team System" will be available in the Pro level SKU with the upcoming release of Visual Studio Orcas.
This is fantastic news because it will put XUnit style unit testing functionality in the hands of more .NET developers than ever before! In a sense, this moves XUnit functionality from leading edge to the mainstream. And, while I agree with Brad Wilson about moving the unit testing infrastructure into the .NET framework, this is still quite a significant accomplishment.
Congratulations to Naysawn and his team for responding to customer feedback and making this happen! And, congratulations to all those unsuspecting .NET developers out there on their impending XUnit enlightenment!