It's time to install Visual Studio 2017: Microsoft released Windows 10 SDK Preview Build 16232 for developers, and the company said the Windows SDK will now "formally only be supported by Visual Studio 2017 and greater." So if you want to use the latest-and-greatest in your software, you're going to have to stay up to date with one of the various iterations (Community, Professional, Enterprise) of Visual Studio going forward.
Besides the requirement to stay hip--or at least as much as using a current IDE can be considered "staying hip"--Windows 10 SDK Preview Build 16232 brings "under development changes to the API surface area" and the usual bug fixes. This update is supposed to help prepare the Windows SDK for the upcoming Windows 10 Fall Creators Update, builds of which are currently being distributed to Windows Insider Program members.
You can use Windows 10 SDK Preview Build 16232 alongside previous versions of the Windows SDK if you want to submit apps for the Windows 10 Creators Update (note the missing "Fall") or earlier. You'll also want to use older versions if you rely on ecmangen.exe, which is being removed:
Ecmangen.exe will no longer ship with the Windows SDK. Developers who rely on ecmangen for event manifest creation are advised to install the Windows Creators Edition of the SDK to obtain the file. Developers may also use notepad or other XML editor of choice for manifest creation. A schema file is available on MSDN to aid in manifest creation, for tools that support it.
There are, as always, a few known issues with this preview build. Microsoft said Visual Studio's Designer view might fail to render, that compilation fails on pre-Windows 10 platforms, and that WRL projects containing a WinRT component might also fail to compile. The company shared the explanations and workarounds for all of those issues in the blog post announcing Windows 10 SDK Preview Build 16232.
But there does appear to be another problem: Three developers have commented on Microsoft's blog post saying they can't install this preview build. So if your installation fails as well, know that you aren't suffering in silence. You can (at least attempt to) install Windows 10 SDK Preview Build 16232 from the developer section of the Windows Insider Program. The various versions of Visual Studio 2017 can be found on its site.