Its looking like the B767-300 is staying on the Chicago route for the winter.
It was originally due to run until 27th October, then last week it was changed until 14th November, and yesterday was changed to 22nd November, so seems like each week in winter is being loaded as each week in summer passes.
Since the change from a B757 to the B763 on the ORD-MAN run, the B757 in AA's colours is at ORD no more, save for a couple of domestic runs.