My understanding is that any new a/c not on the fleet plan (I think DAL had two 777s on order, so 'south' guys get dibbs on them) would go to all bidders. The real wrench in the gears--so to speak--is if DAL gets tired of waiting on the 787, and converts those orders to 777-300s. Man, that'd be a food fight. Suppose that's a Q for another day...or maybe someone actually has the answer for that too!
Chuck