Schedule change is almost a sure thing based on my previous experience with far-ahead-of-time bookings. Also keep a look out for equipment swaps, as the international tariff says:
(C)SCHEDULE CHANGE IN THE EVENT, AFTER TICKET ISSUANCE, SCHEDULE CHANGES ARE MADE BY AA THAT:
(I)AFFECT A PASSENGER'S DEPARTURE AND/OR ARRIVAL BY 2 OR MORE HOURS;
(II) RESULT IN THE ADDITION OF AN INTERMEDIATE STOP ON THE PASSENGER'S ITINERARY;
(III) RESULT IN A SUBSTITUTION OF EQUIPMENT NOT ACCEPTABLE TO THE PASSENGER; OR
(IV) IF A CANCELLATION OR A CHANGE IN EITHER AIR OR TOUR ITINERARY IS INITIATED EITHER BY AA OR IT'S TOUR OPERATORS WHICH IS UNACCEPTABLE TO THE PASSENGER, THE PASSENGER WILL HAVE THE OPTION OF CANCELLING WITHOUT PENALTY, OR REROUTING ON DIFFERENT FLIGHTS TO/FROM THE SAME OR DIFFERENT DESTINATION.HOWEVER, THE PASSENGER MUST PAY ANY ADDITIONAL AMOUNTS RESULTING FROM THE REROUTING.
(bold mine)
I was successfully able to change an ORD-LHR to a different day because they swapped out the 787-8 for my particular day of travel... Allowing me to instantly clear a SWU rather than be waitlisted.