Very few people flying DL will feel the need to spend 250k on Amex
I think one will see a lot more PM and a lot fewer DMs.
If you plan to hit DM with mainly card spend in 2017 do it NOW with the help of Delta Reserve MQM from friends.
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).
The Reserve card also offers SkyClub access, which will be handy for any fallen DMs in the future. It also explains the new skyclub choice benefit options- DMs with the reserve card can now avail of other options instead of having duplicative access.