Upgrading windows server 1709 to 1803?

Lars Andersen, in-place upgrades from Windows Server 1709 to Windows Server 1803 were part of the initial Insider previews, and were promoted as a feature of that version early on.

https://redmondmag.com/articles/2018/01/23/windows-server-in-place-upgrades.aspx

However, it looks like they dropped that feature when they announced, in late March, that the SAC versions would be focused entirely on "modern applications and innovation scenarios such as containers", and would drop most of the infrastructure roles.

https://cloudblogs.microsoft.com/windowsserver/2018/03/29/windows-server-semi-annual-channel-update/

Accordingly, 1803 has even fewer infrastructure services than 1709 (which dropped Storage Space Direct just as it was released). So an in-place upgrade would have likely stripped out features from a 1709 installation, causing issues for administrator who (rightfully) expect an in-place upgrade to maintain roughly the same feature set.

I haven't seen any indication if 1809 will offer an in-place upgrade, since all the attention has been focused on the LTSC Windows Server 2019 version.