This is obviously a back door way to kill off rollover miles, touted as such a munificent gesture and a big difference between SM and other programs just a couple of years ago. I have 15,000 rollovers right now, so one flight to NRT would make me FO on miles but leave me well short on MQDs. Why didn't DL just be up front about getting rid of rollovers?
Also, I guess mileage run will now be redefined as anything at least 10 cpm.