Yes, generally it would require an overbooked flight for any op-ups for *Golds to happen, which is unlikely on Dec 25.

As noted, never hurts to ask with a big smile every step of the way to the gate!
Agents have heard all the reasons 'why' we 'should' be given a comped upgrade, so don't try to pull one over on them, just tell them what you want with a cheeky smile and cross your fingers under the desk. It's worked for me......very rarely