*Well, sometime ago Famitsu mentioned that White Knight Chronicles 2 was under development in an article that showed the new DLC of WKC. So it may be one considering that Sony has not officially say a thing about the game.
*The next one could be LEGEND OF DRAGOON 2 (if Sony delivers this I will buy 3 PS3 slims to thank them lol XD).
*Resistance 3 could be revealed but I dont think they will show the game in a Japanese convention, because they dont like shooters.
*Dark Cloud 3
*Lost Galaxy 2
That is all the possible games that come to my mind XD.