This is spot on -- UA's devaluing MP was only sidetracked by the operational mess of the IT integration. DL has written the playbook and AA will eventually follow. In the 80s and 90s smaller players have very generous programs - those kept the majors honest - and in this period as the programs were still flying focused and there was still a big growth curve, even the big guys were quite generous. Now with less competition, niche carriers that have stingy programs, foreign airlines that are devaluing their programs and much more profit coming from non-flying transactions DL, AA, UA and US have little incentive to do anything but gradually turn the screws until they actually see it is costing them profits. Again, DL did it and got away it and UA was only caught by its operational meltdown.

Some of the best FT advice is not to bank miles for too long. I would add to enjoy the perks like very high upgrade percentages and AA's very generous eVIP program while they last.