You need two parts to scale this, a GPO and a batch file on a network share.
GPO: Computer Configuration - Polices - Windows Settings - Scripts - Startup - Enter file path \\ServerName\ShareName\HostCopy.cmd for example.
Batch File: (HostCopy.cmd) xcopy /D /y "\\ServerName\ShareName\HostCopy.cmd" "%SystemRoot%\system32\drivers\etc\"

Upon bootup (or reboot) the Hosts files will get updated. You have to do this at boot so that the batch file has the permissions to write to the system folder.