Sony Online Entertainment, and their partner Wizards of the Coast, have announced that they will be discontinuing game services for Magic: The Gathering - Tactics next year on March 28th, 2014. There was no specific reason behind the shuttering of the game.
People can no longer create new accounts for the game, all websites and forums associated with the game will be shut down as well and as of November 18th no new card decks will be available for purchase (although existing decks in a player inventory will be usable up to the end).
Sony has also reminded people that any Station Cash they have in the SEO Wallet is not tied to any particular game and is good for purchases in other games.
They have also stated that they, "will not license or authorize the operation of a Magic: The Gathering - Tactics emulator or fan operated Magic: The Gathering - Tactics server.", so you can just give up on that idea right now.