Per a Delta press release:

The expansion of domestic Delta One comes with an industry-leading perk: Starting April 1, 2018, Delta Sky Miles Medallion Members will be eligible for unlimited day-of-departure Complimentary Upgrades to the Delta One cabin on all domestic flights, including Hawaii. This is the airline’s latest move to simplify its SkyMiles program while making it more rewarding for customers.

I suddenly feel the need to fly from Boston to Los Angeles...

http://news.delta.com/delta-one-serv...mestic-markets