On doing a dummy booking the aircraft shown is the 330 . Etihad are phasing these planes out slowly . The normal 787 flown on this route may be due to maintenance check on the dreamliner ,so a substitute 330 could be a replacement . What I would do in your case is book A & C towards the rear of the plane , and providing the flight is not over sold , you will probably end up with a middle empty seat , if they switch it back to a 787