OSDBuilder can Update Windows 7 SP1 and Windows Server 2012 R2 by using Update-OSMedia. Creating a customized OS (OSBuild) is not supported, nor are there any plans to develop this in the future
There are no long term plans to continue to support Windows 7 SP1 and Windows Server 2012 R2 in OSDBuilder
There are no plans to include support for any other Legacy Operating Systems