I have an early October 2020 RT on United and a early March 2021 on COPA booked. No issues at all in ticketing at this time for any flights.. my only concern is how the Argentine government is going to be handling foreigners (Covid related) when entering the country. I haven’t read anything about that so far.
United is offering free changes on tickets booked prior to August 31 (but they’ve been rolling out that date and I expect an extension) COPA is offering free changes however travel must commence by December 31, 2020 for that to be applicable