Depends if you use the FQDN as the server name or not which as of version 10 Cisco changed back to proposing FQDNs in place of IP addresses mainly for Mobile and Remote Access (Collaboration Edge) reasons. It could also break SRV routing, etc if you use that anywhere.
What would be the reasoning behind doing this, it's not like the CUCM servers are actually added to a domain as servers.
Chris