I think that (Air)NZ will be able to up prices for subclass of J after the divorce.
Right now, if you/a person wanted, they could book a VA flight Au - NZ or vv in subclass of J for about $6xx or $7xx, but VA is selling its subclass of J higher.
Personally, I prefer flying the wide jets, so would go NZ in premY, but if I was that way inclined, I would book subclass of J for an VA metal flight plane, but using an (Air)NZ flight number on it.
I am sure after Oct, (Air)NZ will be upping prices for TransTasman flights, it would then after that keep all the revenue, and would not have to share it with VA, either $ wise or FF points wise.
Its lounges also would be less full, as VA J pax would no access.
Lots of speculatory about it, but I think that (Air)NZ would probably gain more from this divorce, than VA would.
VA might go the PP priority pass system for lounge access.
Don't think they (VA) would continue to put J pax Koru's way, and pay (Air)NZ for the previledge.