Microsofts work on making the cross-platform open source .NET Core a viable successor to its .NET Framework has been amazing recently, the next .NET version in late 2020 will deprecate the Win32 exclusive Framework entirely, it's also a big part of the now Microsoft owned Xamarin project which is used a lot for cross-platform app development.
Presumably as with MSHTML and EdgeHTML in the .NET Framework, this new Blink engine will also be exposed for either rendering entirely or using within applications, giving .NET5 its own equivalent.