Hello - basically as far as Autostart is concerned, there should be no intervention required as long as each node short name and IP address stays the same - as it probably would. Autostrart only cares about the proper resolving in between nodes, so stopping the Autostart services, joining the nodes to a new domain, and restarting the services should be all there is to it. I'd check the list of users in Autostart if they are configured with fqdn's maybe but that should be all.
Of course, MSSQL itself may need more work, but I am not an expert in that area...