upgrade and change domains

Way back, when we first installed Exch2000 on Win2000, we created a ‘resource’ AD domain for the mail servers to sit in because our users resided in multiple AD domains.

 I now see no reason for the mail servers to reside in that domain

 I am planning an upgrade from exch2007sp3 to exch2013 and I would like to eliminate this domain at the same time.

 I plan to migrate the mailboxes to the new Exch2013 server.  The user accounts will remain in their same domains.

 Anyone see a problem with this?

 Thanks