new damage model will be pushed to the WW2 arenas 
It already is. Have you not noticed the revised damage screen listing? There are also new levels of damage like individual H-stabs being shot off.
That is already "pushed to the WW2 arenas" -- we've got it!
What they might do from this point and into the future is to add new things to incorporate that new damage, but it might be only on a new-development basis. Meaning, they might add more wing panels to blow off (instead of just "tip" and "wing" and "full wing"), but it wouldn't apply to the older non-updated models. <-- doubt that's in the works, but it's a thought.