I don't know, seems too obvious. Rememeber what people initially thought when Paul gave us the picture of the two guns? They initially thought it was an Assassin's Creed hint but it turned out to be pointing towards LittleBigPlanet.
I'm not saying Sagat doesn't have a chance. I'm saying it's too obvious that it's unlikely. A streetfighter rep in general sounds little more likely. ^^;
I speculate Kat. Mostly because the pic has to do with gravity, think about it, push ups. It's military themed as well, in Gravity rush there are run ins with the military. The shadow could also point towards Kat's shadow, or her cat. Blonde hair is a minor clue as well, mostly because it's too common of a clue.