I also think we're missing the point that DL doesn't want people "trying" to hit the next tier. They'd much rather have everyone just under the qualification threshhold and not have to provide the higher level of benefits.
I know a LOT of people who travel extensively for work. I'd say less than 10% of them would consider taking an extra trip in order to qualify for the next elite level of status. Fewer than 3% would consider taking an extra 2 trans-con trips. The vast majority of fliers -- even very frequent fliers -- don't like to spend time in airplanes. I really don't think DL is losing much revenue because people give-up flying them because it's too long a distance from GM to PM.