not a big deal but if you used FQDN for clients to resolve the WSUS server name in your GPOs, you will need to update it. If you just used hostname it's fine I guess
if you're using SSL between server/client, it gets complicated, you will probably need new certs with the new domain FQDN inside unless you were using a wildcard cert
if you deployed WSUS with a full version of SQL, ensure the SQL service accounts will either work after the domain change given you have sufficient AD trusts in place or change your service accounts to reside under the new domain
