The strategy seems so unclear here.  Is the expectation that all casual games should be written in HTML/WinJS for Windows 8 Store Apps? 

I would be happy to see MonoGame to be more officially supported by MS.  MonoGame needs investment - like removing the dependency on Game Studio and better support for Windows Desktop based apps.  How about Microsoft open-sourcing XNA and so that Xamarin can pick it up?  Remember, XNA still doesn't support TouchPanel properly on Windows 7/8 desktop apps.  It really looks like development has stopped.