This is definitely the coolest thing I found today: running XNA in Visual Studio 2013. Thanks to the unofficial contribution, it is possible to use XNA 4.0 in Visual Studio 2013, 2012 and 2010. Find the appropriate download links at codeplex.
This brings XNA development back in the latest version of Visual Studio, but sadly, although you can develop Windows Phone 7 XNA games in VS 2013, you cannot deploy them from Visual Studio since it doesn’t support WP 7. But that can be fixed since the final XAP is valid and XapDeploy can be used to deploy built games to emulator.
So as XNA projects can be loaded in the same solution as MonoGame projects, porting old games will be easier. Since the project promises porting XNA to DirectX 11, we now have two projects with same scope in mind.