[Update: Further details on the sealed play mode and potential cost can be found here. It sounds like players will not need to pay for booster packs, rather the game will come with two sealed deck slots in which you can edit and save the cards that you get via booster packs. If you'd like to save more than two decks, each slot will cost $1.99 each and give access to draw from the pool again. Each card set has 180 cards to draw from, and the game will give you six 14-card booster packs to open (for a total of 84). So, from the sounds of it, everyone can still play sealed tournaments with 2 customizable decks but if you want more decks you can pay more.]
Wizards of the Coast has announced some exciting news for Magic 2014: Duels of the Planeswalkers -- sealed play! This new mode will allow players to open booster packs, create a brand new deck, and duel against other players or AI. Incorporated into this mode is a six-deck ladder, each with their own respective Planeswalker sealed pool containing 84 cards.
Love them or hate them, Slivers are also making their way into DotP. Wizards also announced a new type of sorcery card -- Hive Stirrings -- which will create more Sliver tokens. I've personally never played with Slivers but they seem to have a love/hate relationship with fans.
I for one did not expect the DotP series to ever have sealed play or deck creation in any manner, so this is a delightful surprise. Can't wait to get my butt kicked this summer!