HTML5 was one of the biggest reasons why Silverlight lost its charm. It offers rich format tags, and support to play online videos without the need for any plugins like Adobe Flash or Silverlight. However, Microsoft will stop supporting it from October 2021.
Silverlight is back as open source OpenSilver
How is OpenSilver different from Silverlight? First, it is plug-free, which means it will work across the browsers without you installing anything. Second, it is an open-source reimplementation of Silverlight. It uses another open-source software called WebAssemply, which is supported by all the browsers. Developers can use C#, XAML, and .NET to client-side Web development.
You can create new apps and to modernize existing Silverlight applications. It goes without saying that you need to recompile your old Silverlight application with OpenSilver in order to run on those browsers. Interesting to note that OpenSilver GitHub repository mentions about CSHTML5. It is C#/XAML for HTML5.
As of now, OpenSilver is in Technology Preview. It currently covers around 60% of the Silverlight API, which includes the most common functions. In 2020, there is a plan to support Open RIA Services and Telerik UI for Silverlight. Since OpenSilver depends on Blazor and Mono for WebAssembly projects, it will be updated in sync with it.
The company behind managing OpenSilver is Userware, which was founded in 2007 in Paris, France. They have experience in developing applications using Microsoft technologies and will keep improving OpenSilver.