It is expected that the Windows 10 Version 1903 released in the spring has been developed, and the main task for the rest of the time is to improve the stability of the version. By convention, Microsoft will also release an Insiders Preview version of the next major version update in advance, which is Windows 10 version 1909 (Windows 10 19H2).
— Nicola Ivkovic (@nicolaofficial4) January 25, 2019
Some netizens got the answer when they consulted Microsoft on Twitter. It will be released in the next few weeks. The earliest time may be pushed to in late February or March. At that time, Microsoft will also issue an announcement in advance to reset the Insiders Preview program and wait for the user to re-join this program. Finally, after the completion of the join, the new test version will be released. Of course, the stability of these early Insider previews may not be so good for users, so these versions should not be used as a daily version.
There is currently very few info about Windows 10 Version 1909, and perhaps the most anticipated new feature is the Sets feature.