If you are indeed concerned about rollovers of elite qualifying miles, I'm sorry you were under this misimpression that this is how frequent flyer programs worked. Moreover, it's a relatively new feature for Delta at all, and pretty meaningless as Medallion Qualifying Dollars do not rollover.


But I'm not sure if you're understanding what's going on here. You don't *lose* the miles earned the year before. If I flew 30,000 miles on United last year, I will qualify for their base elite status (Premier), and start 2014 with no "premier qualifying miles." On Delta, I would be a Silver, and start the year with 5,000 elite qualifying miles in my account. But with both airlines, all 30,000 miles will remain in my account for me to spend until they expire. Delta does not have an expiration date for its miles. For United, miles will expire after 18 months of inactivity (similar to most carriers).