Longtime Tekken producer Katsuhiro Harada recently replied to a tweet asking about a possible PS Vita version of Tekken X Street Fighter (the game that the Tekken team will develop that's set to be shown once Street Fighter X Tekken is out). His reply:
"I'm considering now."
So there might be a PS Vita version of Tekken X Street Fighter if Harada feels it's worth the effort.