I see the Japanese release date as the most likely time we'll be seeing Kat and Emmett. Gravity Rush was popular in Japan, and as of now I do believe that Toro is the only "japanese" character in the roster. Having Kat there too will probably greatly help the sales.
Heihachi would like a word with you.
Spike, Heihachi, Raiden & Toro are big in Japan - but I agree, Kat would be icing on the cake (Gravity Rush won TGS Game of the Year).
So it's release coinciding with Japan's makes sense.
PaRappa as well. He had an anime there, after all.