According to Greg Leeds, President of Wizards of the Coast, "With more than 12 million players and fans in more than 70 countries and 500,000 units of Duels of the Planeswalkers sold on XBLA, Magic is experiencing record growth and delivering players a truly integrated gaming experience across both digital and real world."
The sequel will include new modes, decks and challenges. Perhaps the most important question of whether or not it'll include full deck customization remains unanswered.