That information is wrong. Only 767-300s will be configured to two-class service. 777s and 767-200s (which serve the JFK-CCS route) will remain 3-class. AA has already gotten rid of 3-class A300s, which never served Latin America in the first place. Santiago de Chile, Buenos Aires, and Sao Paulo get 777s, and the few flights that are not 777s to these cities are likely to become 777s because of these changes. As of now, no Latin American destination with three-class service will loose all of it. Assuming the same equipment schedules, one MIA-EZE and MIA-GRU flight, DFW-SCL, and both MIA-GIG flights will loose three-class service, along with GRU-ASU and EZE-MVD. However, because American Airlines is going to be able to increase aircraft utilization, it also means that more 777s will possibly be used to American's six deep Latin America destinations, and with new two-class equipment and increased aircraft utilization, it means that flights like MIA-ASU, MIA-CNF, and MIA-MVD non-stop, instead of with stopvers in GRU, GIG, and EZE, respectfully, can become more viable in the future.
As for route cuts, I don't know, but I really doubt you will see any route cuts, though frequency cuts are likely. AA's newest Latin American route, MIA-PUJ, was announced yesterday.