Could it happen? Chances are no, why? Because we were going to get it through Naughty Dog but that game ended up morphing into the Last of Us. Now the Last of Us will undoubtedly share a lot traits from Jak and Daxter, but will be more akin to Uncharted stylized in the vein of I am Legend. Recently we got Jak and Daxter HD which included all of the Naughty Dog Jak and Daxter games, minus the racing catastrophe.
The Collection contained NO HINT as to a future Jak and Daxter game, thus leaving Jak and Daxter 4 in doubt. So will it happen? No, consider the series dead. Why? The HD Collection sold very well, but likely not enough for Sony to consider there to be enough fan support for the series, this was also probably another reason why Naughty Dog does not have a third team working on Jak 4. So get the collection and call it quits, because Jak is no longer at Sony, he is in All-Stars, likely, but that's it son, he's the Captain Falco of Sony now, say hello to him when he appears in a 3D Remake ten years from now.