First of all don’t panic, Windows Server Desktop Experience Mode has not gone for good!
Although for sometime now core has been seen as the preferred version of Windows Server for the enterprise. From experience, most customers will still end up installing the full GUI version.
So why remove it from the latest Windows Server release 1709?
Windows Server, version 1709 is the first release in the new Semi-Annual Channel for Microsoft. The Semi-Annual Channel release is aimed at customers such as those that have a rapid development path or perhaps those acting as hosting companies who wish to keep up with the latest Hyper-V investments. Microsoft plans for Windows Server products in the Semi-Annual Channel to be released twice a year, with each release in this channel being supported for 18 months from the initial release. Microsoft have stated that, most of the features introduced in the Semi-Annual Channel will be rolled up into the next Long-term Servicing Channel release of Windows Server. However, the actual editions, functionality, and supporting content might vary from release to release depending on customer feedback.
Windows Server as we know it with the full Desktop Experience Mode will become the Long Term Service Channel of Windows Server 2016. If you want to stay in this channel, you should continue to install Windows Server 2016, which can be installed in Server Core mode or Server with Desktop Experience Mode.
These changes will call for a more informed discussion during project initiation phases. Choosing the correct OS will be based not only on the need for the latest and greatest features, but also an acceptable upgrade cycle for the business, whether the customer is comfortable supporting Windows Server Core and if the the technology being deployed as part of the proposed solution is supported. For example, Remote Desktop Service (RDS) would not take advantage of the new Semi-Annual Channel where as Hyper-V would.
Both releases will be supported with security updates and non-security updates but feature updates to the LTSC would happen less frequency purely due to its release cycle.
Release channels and installation options
|Installation option||Semi-Annual Channel (Windows Server)||Long-term Servicing Channel (Windows Server 2016)|
|Server with Desktop||No||Yes|
For much more on this subject, checkout this Microsoft blog: