Let's say you buy a nonrefundable econ ticket, then subsequently pay for a $$ upgrade. You of course get refared to P/Z as a result of buying that upgrade. At some point in the future, the originally-purchased econ itin drops in price. The F fare for the same itin also drops so much that directly buying into F would now be less $$ than what you actually paid for your econ ticket + upgrade fee.

Are there any options to take advantage of the price drops in this scenario? My understanding is that upgrade fees are nonrefundable on changes and cancellations, so I'm not sure that the usual change/cancel/rebook with resultant credit strategies work here.