There are a number of changes coming to Team Foundation Server requirements in TFS 2018. Details on requirements across versions of TFS can be found in requirements and compatibility. This document is intended to help current users of TFS 2017 who are upgrading to TFS 2018.
TFS 2018 will not support Windows Server 2008 R2, Windows 7, Windows 8.1, or Windows 10 Home edition. We have never recommended installing TFS on client OSes except for evaluation purposes or personal use. Even for these use cases, we now recommend creating a free VSTS account. We will continue to support Windows 10 Professional and Enterprise editions.
TFS 2018 will no longer support SQL 2014, but will continue to support SQL 2016 and will add support for SQL 2017. We typically strive to support at least one "overlapping" version of SQL between major releases of TFS in order to make it easier to upgrade TFS deployments incrementally.
TFS 2018 discontinues support for the TFS Extension for SharePoint. For more information, go here: https://go.microsoft.com/fwlink/?linkid=852977.
TFS 2018 will no longer support the XAML build system. For more information, go here: https://blogs.msdn.microsoft.com/bharry/2017/05/30/evolving-tfsteam-services-build-automation-capabilities/.