Q. Can I migrate the domain of Delivery Controllers? 
A. No. Domain migration is not supported.

Q. Why domain migration of Delivery Controllers is not supported?
A. Windows OS works on SIDs. Changing/Migrating the domain will change the SIDs of machines. Citrix also uses the domain SIDs as identifiers and saves all the SIDs in the site database. 
Domain migration will change the SIDs and Citrix will not be able to resolve the new SIDs with existing SIDs in the site database. 

Q. Can I migrate VDAs to a different domain?
A. That is possible, however, all the machines need to be readded to the CVAD site so that new SIDs can be updated in the site database.
For MCS catalogs you have to recreate the catalog or add machines as manual machines.