For a long time now C++ has been the dominate game development language. Many AAA quality 3D engines are available to fit any budget.
My question is, with the rise of X
It is not just the studios to consider, it is the audience. Chances are that as long as Sony and Nintendo are around, they are unlikely to move the a C#/XNA platform. At least for Nintendo, when you have the mass-market appeal that they currently do, they will continue to dictate their development platform.
I love XNA, since I can now write applications for my Zune, but C++ for a broad-based development platform for gaming is going to be around for a long time. There might be an influx of new indie developers for Microsoft devices, but we are a far way from seeing XNA be used across the board, if ever.