http://www.ign.com/articles/2014/07/25/sdcc-2014-tekken-x-street-fighter-has-not-been-cancelled
Tekken X Street Fighter is still happening, according to producer Katsuhiro Harada.
As reported by Polygon, Harada broke the news by responding to a fan's request for an update at San Diego Comic Con. According to Harada, the crossover of the two franchises is "still in development and it's still moving forward."
He claimed that the numerous other fighting games that Bandai Namco has in development is making it tricky to find a window for Tekken X Street Fighter's release, but the game "is proceeding. It hasn't been canceled, so please relax."
Tekken X Street Fighter was announced at SDCC all the way back in 2010.