Microsoft promised a modern version of File Explorer a few years ago, but the project never reached its final stage despite the many drafts that occasionally appeared in Windows 10 build previews.
The company reportedly focused more on improving the appearance of the existing Win32 version of File Explorer, and the latest "fixed" update of Windows 10 brought for example a a new dark subject.
However, File Explorer will receive a major facelift in the next major update of Windows 10, according to one Publication of HTNovo.
The company is reportedly considering new ways to bring Fluent Design to File Exploser, and if everything goes according to the plan, the trial releases will be released to users later in 2019.
However, the development phase seems to take some time, so we will probably see the new File Exploser on the big update of Windows 10, which will be released in April of 2020.
So Windows Insider users could get a taste of the new File Explorer at the end of 2019 when Microsoft has developed Windows 10 20H1 and will have builds build on Fast Ring.
Currently the experimental Windows 10 20H1 is already available for Skip Ahead subscribers, but it does not yet have major changes.