Honestly, I have no idea how All-Stars will do. It will be interesting to watch. Getting both copies with the PS3 version might actually push Vita sales somewhat. My only concern is that the Japanese might stay away from a fighting game developed in the west.
Also, one minor note: The Fate universe is still extremely relevant in Japan, with the Fate/Stay Night movie in 2010 and the Fate/Zero anime series just wrapping up.