And American won't do anything until United does... and so it goes ...

I'd think that UA would be the first to go because it would be hurt more than AA, as it would face a yield squeeze (by ultra-frequent flyers migrating to flat-bed on competing airlines) on both the (cash-cow) Pacific and London markets, while American's exposure is more limited to London as all of its Asian routes are to Japan and none of the Latin American carriers are going fully flat).