As I said in another thread, I think Demon's Souls and LoD are off the table. They said it was a big one and that millions would be looking forward to it. To me, that suggests the size of the IP and how many it's sold, either one game or the series. Neither Demon's Souls or LoD have sold enough for millions to be waiting for it.
I also think that the reimagining refers to how the game levels are set up and how it plays. Something that Blue Point wouldn't really have to touch unless it was a much older game/series. So, if it's a Sony IP, my guesses are Syphon Filter, Twisted Metal, or, maybe, Ape Escape.
Then again, it could be an IP that Sony doesn't own, but got the exclusive rights to, even if only for a year. Like MGS or Silent Hill.