Microsoft is holding its Windows Developer Day for the Creators Update today, which is a livestreamed event that discusses what's new for developers in the upcoming feature update. At the event, the company confirmed that the latest SDK Preview is feature-complete.
The SDK Preview build in question is 15021, and it was released five days ago. The only new features were improvements to the Windows namespace, updates to debugging tools, and a number of new API additions and changes.
While there are no known issues in the build, that doesn't mean that it's done. Feature-complete means that Microsoft is done adding new features, but the SDK will presumably continue to be refined until its general availability.
Unfortunately, the latest SDK Preview still doesn't support compiling a UWP app in 64-bit ARM, or ARM64. While ARM64 has been an anticipated feature for Windows, it now seems clear that it won't be coming in the Creators Update, just in case that was something that was on your wish list. At Ignite 2016, we were told that the reason for the lack of ARM64 support was because there are no Windows phones with more than 4GB of RAM.
If you want to check out Windows 10 SDK Preview build 15021, you can download it here. You'll need the latest Windows 10 Insider Preview build, as well as the Visual Studio 2017 Release Candidate.