We're still waiting on OPM to finally reveal this mysteriously new Square Enix game, but before that happens, this bit of info looks to be a pre-cursor to that eventual announcement. Via Siliconera, we hear that a new trademark has been filed by the RPG giant - a trademark for a "Vanguard Storm".
It's pretty hard to go by words alone, but what we do know is that it doesn't seem to have anything to do with any of its current IP (as opposed to yesterday's trademark for Front Mission Evolved, which clearly points at their futuristic tactical RPG series).
As such, this so-called "Vanguard Storm" seems to be a prime candidate to be the title of their new action-RPG. It's not an absolute hypothesis - it could, after all, just be a trademark for something else that's entirely not a game.