The announcement acknowledged that the bulk of the integration and shuffle of flights and equipment cannot take place until a single FOS (Flight Operating System) is in place for the airline. But they see these opportunities now where they can save some money by enduring some crew inefficiencies to take advantage of efficiencies of having the right airplane for the demands of a particular route.
The have been doing this domestically for a while now. This is the first time there will be any realignment of widebody equipment out of its legacy routes. Since they say it is only the start, once the single FOS is in place, there will probably be 767-300s based in PHL, A330s based in ORD, and many more surprises in store for international crews.
It doesn't really matter how the arbitration board rules on seniority and what fences they put in place. The company has to sign off on it, and if there are restrictions that would cost the company money, they will simply tell the arbs what parts are no-go (the arbs probably already been informed of what the company needs in the way of lack of restrictions and fences.)
