I find this one hard to believe for several reasons. For one, Street Fighter and Tekken play nothing alike, so combining them would surely necessitate the alienation of one or both of the series's fan-bases. Secondly, Capcom doesn't generally announce a new Vs. game until the last one they've announced has been released. Why should they compete against themselves by announcing Marvel Vs. Capcom 3 and Tekken Vs. Street Fighter in the same time-frame?
Also, Tekken? Really? Does anyone play Tekken anymore?
Still, I hope this rumor is true. The more Capcom fighting games that get brought into existence, the better. If this game does come to be, I hope it doesn't get landlock to Japan like Namco and Capcom's last collaboration, Namco X Capcom.
How about you? Do you want some Devil Kazuya Vs. Evil Ryu action up in this piece?
Namco and Capcom working on Tekken Vs. Street Fighter- [The Kartel]