It's my understanding that the agents have a bit of flexibility when it comes to handing the re-routing of cancelled flights. Both in routings and number of coupons.
Last year Mrs WF & I had sectors NRT-MEL-PER. The NRT-MEL got cancelled. We were re-routed NRT-SYD-PER even though that should have made our later PER-SYD flights "ineligible" due to 2 trans Oz segments.
Talk to the AA RTW desk people.
YMMV
Fred