https://arstechnica.com/gadgets/2017/08/fall-creators-update-hitting-the-home-straight-with-focus-on-stabilization/

The Windows 10 Fall Creators Update, aka version 1709, is due to be finished next month. Accordingly, the builds released to the Windows Insider Program are now heading toward stabilization, with bug-fixing the priority.

This has a somewhat greater significance than was the case for prior Windows 10 updates because of the "Skip Ahead" scheme Microsoft introduced a few weeks ago. Most members of the Insider Program will continue to receive Redstone 3 builds and head toward stabilization and finalization for the Fall Creators Update release. Those who opted in to the (limited) Skip Ahead group, however, will imminently be switched to a different Windows branch. This branch will begin development of the Redstone 4 release that's due in March 2018.