I agree, I think it would have been a great idea for Microsoft to continue with XNA and integrate it with the new Windows 8 Metro/store etc, instead they did not, who knows why?
I think the final determination of Microsoft and indie game developers will be what they do with the NextBox. Ive already left XNA and have been using MonoGame and MonoGame only (I only use XNA to compile content once in a while). The Windows DirectX platform of MonoGame will probably release soon (the current released windows version uses OpenGL), you can already use a early version of it by downloading from the MonoGame github.
The DirectX MonoGame platform uses SharpDX and Direct3D11, they have already started expanding the API further than XNA (multiple window support, RenderTarget3D class, etc...)