Don't worry, it's still in the works.
When Tekken X Street Fighter was announced back in 2010, series producer Katsuhiro Harada said they'd wait for just the "right time" to release it. Now, almost four years later, fighting fans everywhere are still waiting.
The good news is that during a San Diego Comic-Con panel (via Polygon ) Harada said the game is "proceeding." He added that between Tekken 7 , Rise of the Incarnates and the ongoing free-to-play titles Tekken Revolution and Soulcalibur: Lost Swords , it has been difficult to find time for Tekken X Street Fighter . Well, that's understandable.
If you've forgotten, Street Fighter X Tekken launched over two years ago. It was damn good, too.
Related Game(s): Tekken X Street Fighter