They really need to put loads of concentration on C#/MSIL.
Many games for Windows are now using .Net to install or even contain the main game dynamics. Sorry but Mono does not cut it and rarely works against native .Net code.
It should be their new year resolution to get the latest .Net working.
Since active Mono development has stalled, I wouldn't be suprised if the code would be imported into Wine directly (eventually). After all, it's a Windows specific functionality, especially right now since the cross platform endorsement somewhat stalled.