Since I anticipate losing my FO status next year, I asked Delta about my unused 500 mile segments. Their reply was "If you are no longer a Medallion you may use your 500 Mile Upgrade points on a stand-by basis. Your name may be placed on the stand-by list at the departure gate on the day of travel.
We appreciate your interest in Delta Air Lines."
I don't know if it's worth "hanging on" and doing one more Delta trip next year to try and use up the upgrades (fingers crossed) or to take the loss and move on
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