The real bottom line for the US3 is "We don't have to try so hard to keep you loyal now that it's just three of us." It's like NBC/CBS/ABC or Ford/GM/Chrysler back in the 70s... competition really wasn't as vigorous as advertised and both those oligopolies produced a lot of bad product by today's standards.

In looking at changes in habits since the worst of the changes were put in (i.e. miles determined by fare and not distance), I'd say the biggest hole is the alliance flight on a good fare that also earned a lot of RDMs (and EQMs). A great example was an IAD-CPT RT for $600s on AF/KL a few years ago that returned a lot in DL miles under the old system. Nowadays I'd want an even lower cost or a bullseye hit on some bucket-list place.