I don't want to complicate things but these scenario have real time possibilites.
EX

note fares have nothing to do with current reality)
T-class ticket (non refundable)ORD-IND $95
don't use this ticket but before flight leaves purchase a refundable class ORD-IND $235
Later purchase new T-class ORD-IND now $110, and refund $125?
or- just trade in the refundable ticket for another (higher priced) T-class ticket?
All this really hurts by betz cells.
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JerseyJoe