.NET Standard 2.0 is available now and Microsoft team is working on making UI and libraries standardization that can be shared among developers of multiple products such as UWP, WPF, ASP.NET Core, and others.
.NET Standard is subset of .NET family to build one common library that can be shared among all .NET family products including .NET Framework, .NET Core, Xamarin and ASP.NET Core.
XAML Standard is a common standard to create UI for in WPF, UWP, Xamarin, and Xamarin Forms.
In this video, Stott Hunter, Miguel De Icaza, and Tim Heuer discuss the future of UWP, XAML and support of .NET Standard 2.0 and beyond.