DL has the basics down. Low cancelations and high on-time arrivals. It knows what to fly, when to fly ot, and fills it up for the most part. It's customer service is also good, especially in IROPS. Finally it's profitable. Thus there's no reason for DL to change. Does it suck we don't get as many freebies? Of course, but those days are gone at all three majors. Bulk of customers want rock bottom cheap tickets and care for nothing else. Bottom line the airline's have moved their programs to be more in line with what you give to them. It's how it really should have been. However that's not how it was setup. Instead someone providing very little could reap huge rewards.

Regardless if we like it or not, it's here to stay.