one of the main considerations is whether ePO can 'see' the new domain. There is not really much you need/ can do on the client end.
Hope this helps,
There is not much to be done really, if it is Endpoint Encryption 5.x, then everything should function normally, SSO might have to be reset. If using version EEPC 6.x or later, then when configuring the LDAP sync task on the EPO server, you will want to point it to the new domain, and reset SSO, but nothing will have to be done on the client except for migrating it to the new domain via the standard Windows method (or whatever third-party tool you are using).