macOS Server 5.5
Apple has released macOS Server 5.5, improving the overall performance of Profile Manager on systems with a large number of enrolled devices and changing the minimum system requirement to macOS 10.13.3 High Sierra. The update also resolves an issue that caused high CPU usage and prevented tasks from completing, fixes a bug that prevented device enrollment tasks from completing, addresses a problem where tasks for some devices might not complete if the “Settings for Everyone” profile has been installed, and fixes an issue that prevented NetBoot images from being offered. Note that Apple said separately that it will be removing services from
macOS Server; see “Apple to Deprecate Many macOS Server Services” (26 January 2018). ($19.99 new, free update, 194 MB, release notes, 10.13.3+)
So this will probably be the last usable version of Server.app, no deprecation here yet, it would seem.