Xavier Plagnal currently serves as Studio Design Manager at Ubisoft Shanghai. A visit to his LinkedIn profile reveals that from September 2013 to the present Plagnal worked as Content Director on "the next Far Cry." It doesn't say what exactly he directed for the game, nor does it offer any word on the game's plot, setting or the platforms it may appear on.
Though we can't say for certain that a new Far Cry game is in the works until Ubisoft officially confirms it, the claims made by Plagnal's resume line up with earlier indicators of its existence. In October, Cliff Martinez, a composer best known for his work on the film Drive, let slip in an interview that he was "working on a video game called Far Cry 4." Only a few months prior, Ubisoft Senior VP of Marketing and Sales Tony Key stated that "[Far Cry is] a great brand, and now it's got the recognition it deserves, so we're clearly going to make another one."