This highest tiered status - Diamond level, is achieved only after earning 125,000 Medallion Qualifying Miles in a calendar year, or flying a whopping 140 segments. Previously, and typical of other frequent flyer programs, the highest level of elite status officially comes after earning 100,000 flight miles or 100 segments.
So what benefits come your way for flying just a "tad bit" more? A complimentary Sky Club membership, entitling you to visit club lounges around the world; 125% Medallion Miles Bonus on all paid flights; and the ability to rollover Medallion Qualification Miles for status the following year. These benefits are in addition to ones afforded to the next tier down - the Platinum level, such as waived award ticketing & redeposit fees, complimentary upgrades, and a selection of Choice gifts.
Delta is expected to make an official announcement of these upcoming changes later today.