If I had to guess, it will probably be converted into a freighter. However it could be picked up by an asian charter airline. You’re right, not much demand for these things.
Interestingly, right now UA could use a handful more of these for their new hub-to-hub routes (like EWR-SFO, IAH-SFO, EWR-LAX), but I doubt they’ll be interested. To my knowledge UA and CO haven’t bought or leased a second-hand aircraft for any extended period of time in the past 15 years. Operationally these aircraft aren’t that great for domestic hub operations in the US because if they get delayed it results in about 250 misconnects and probably just as many downline misconnects and wreaks havoc on the system.