I don't see them taking away the MQM qualification option due to rollover and Amex relationship. However, they could simply match UA's requirements with DL's MQD/MQS requirements (probably with higher levels for DM) and add a MQD boost option for AMEX spend (in addition to MQM boost). At those kind of spend levels, I don't think DL will really take a hit by leaving MQM qualification as an option in addition to MQS.