The recent release of Timewalkers: Reign of Fire, (see "Every 'WoW' Loot Card") will be the final set for World of Warcraft TCG, according to an announcement by Blizzard Entertainment on the World of Warcraft Trading Card Game official webpage.
"We wanted to take a moment to thank all of you World of Warcraft Trading Card Game players out there for your support of the game for close to seven years," Blizzard Entertainment said in the post.  "We’ve had a blast working on it, and we knew that Set 21, Timewalkers: Reign of Fire would really grab everyone's attention."
"Set 21 represents something else as well: it’s the climactic last set for the WoW TCG."
WoW TCG has been, and continues to be, a popular game in both Hobby and Mass Market Channels (see "Top Collectible Games--Spring 2013").  For nearly seven years, the CCG based on the World of Warcraft MMORPG has been the way for Blizzard to keep subscribers "in game" offline.  Originally licensed to Upper Deck, the game license transferred to Cryptozoic Entertainment in March 2010 (see "Cryptozoic Gets 'WoW TCG'").
In the FAQs that follow the announcement, Blizzard says it will still allow players to redeem their loot cards on the official website, but that neither Blizzard nor Cryptozoic will continue to host organized tournaments.  They encouraged players to continue hosting their own tournaments by following their posted tournament guidelines.  They also stated they have no specific plans to grant the license for the WoW TCG to another company in the future.
This eliminates the one exception to Cryptozoic’s exclusive deal with two U.S. distributors for entertainment trading cards that took effect July 1st (see "Crypto Cuts Card Customers").  Alliance and GTS Distribution will be the only U.S. distributors for Cryptozoic entertainment trading cards;  Alliance and Diamond are the U.S. distributors for Cryptozoic’s game products. 
Both Cryptozoic and Blizzard are launching MMOTCGs:  Blizzard’s Hearthstone:  Heroes of Warcraft (currently prepping for a closed beta), and Cryptozoic’s Hex:  Shards of Fate (which had a successful $2.3 million Kickstarter).