Namco Bandai has Tekken Tag Tournament 2 prepped and ready to hit arcades this September. Tekken Tag will first arrive in Japanese arcades on September 14 then scheduled for an international release in late September. Namco Bandai doesn't quite have a solid date for the international version so it may end up being released at a later time.
If you're unable to locate an arcade machine nearby, you can pick up a copy of Tekken HYBRID this fall to try out a demo of Tekken Tag Tournament 2. The demo features Ling Xiaoyu and Alisa Bosconovitch as playable characters.