That's a whole different deal, and has no connection to XNA GS whatsoever. It is not a replacement, nor the future of XNA GS.
But people who don't want to give up C++ for C# might find it interesting.
Oh, and it is free only for personal use. For commercial use, you have to pay.
Microsoft XNA MVP
My blog: 12 months, 12 samples :
April Sample: Dynamic 2D Shadows