Or... DL could try and make money! Selling miles/MQMs is almost certainly more profitable for DL than flying people around. Why kill the golden goose? Rewarding unprofitable flyers for loyalty is kind of stupid, but DL's elite program is structured to do precisely that.

If DL actually wanted to make elite status exclusively about BIS miles, then I think they need to rethink how many miles they award for which tickets. A 50% premium for full-fare F or J over the lowest Y fare doesn't accurately reflect the value of those tickets to the bottom line. Even within Y fares, there is too little differentiation.

If the goal is to reward profitably loyal travelers, then move toward a model more like BA, where most coach fares don't help toward status. Or move toward an LH model, where most cheap short-haul fares are 50%, paid F is 300%, and status that is actually worth something takes 100k miles.

Somehow, I don't see too many people clamoring for such a system. And, for now, such a system might be uncompetitive but, if one is using a competitive argument, then it isn't clear that getting rid of the non-BIS miles helps in that regard.

Personally, I think DL should introduce a 4th tier and keep the non-BIS MQMs. It helps incentivize incremental spend, both with cash-paying partners, and continued spending on DL after reaching each threshhold.

The only way this happens is if demand for paid F falls completely off the cliff. Why on earth would you offer F for free to the customer segment most likely to actually pay the premium?