Today AA announced a new fee in addition to use of miles in order to upgrade international fares.
A co-pay of $250 will be required to claim mileage Upgrade Awards used with most Discount and Deep Discount Economy fares when traveling between North America and Europe, Japan and Deep South America, effective December 1.
You can find the
discussion in the AA forum.
Let's hope that UA doesn't decide "monkey see, monkey do". I would argue that UA already does this in a more discrete way. AA has allowed mileage upgrades from rock bottom fare. UA requires the purchase of H fares for mileage upgrades. Still, I feel some angst as to whether UA will feel this is an opportunity to get more from the frequent flyer.