Beta 4 of C#/XAML for HTML5 is out. http://cshtml5.com/
Now with Full support of C# 5.0.
According to the roadmap if everything goes as planned: Most of the features required to easily port Silverlight apps and other C#/XAML-based apps to HTML5 are available in Mid 2016.
If there is a feature we need to make this work with CSLA we can vote for it. What should I vote for?