Microsoft released a new Windows 10 Preview Build of the SDK. It is to be used in conjunction with Windows 10 Insider Preview (Build 19013 or greater). The Preview SDK Build 19013 contains bug fixes and under development changes to the API surface area. According to Microsoft, this build version is the bridge between previously launched SDKs and Visual Studio 2017 and 2019. Users can continue to develop and submit apps that target Windows 10 build 1903 (or earlier) to the Microsoft Store. The Windows SDK will now only be supported by Visual Studio 2017 and greater.
Microsoft has made some updates in Message Compiler (mc.exe), Windows Trace Preprocessor (tracewpp.exe), TraceLoggingProvider.h tools. Microsoft has made signing apps with Device guard signing easy. Their official blog says “We are making it easier for you to sign your app. Device Guard signing is a Device Guard feature that is available in Microsoft Store for Business and Education. Signing allows enterprises to guarantee every app comes from a trusted source. Our goal is to make signing your MSIX package easier”
There are some new changes as well. Microsoft has removed api-ms-win-net-isolation-l1-1-0.lib, Apps that were linking against api-ms-win-net-isolation-l1-1-0.lib can switch to OneCoreUAP.lib as a replacement. bthprops.lib has been dropped in for, ENUM tagServerSelection has been moved from WUAPICommon.H and WUAPICommon.IDL to wuapi.h or wuapi.idl. respectively. You can read the full blog here