In 2018, the value of DR MQMs will drop significantly as it is of no use beyond PM.
In fact I think the number of people with DR card will also drop (although the tie breaker will help the hard core keep it for a while).
I disagree, you'll still want to use the card and spend $60k on it to get the 30,000 MQMs. This won't affect the use/need for the Delta Reserve Card at all!