I am pretty sure Ironclad already promised they would answer the question of "who is chasing the Vasari" before they are done with Sins. There have been not-always-subtle hints that there is a major expansion pack coming out, and they certainly promised to eventually provide more story content
I personally am a bit sceptical wether they will reveal the identity of the "Vasari hunters". Because if Ironclad would reveal who the "hunters" are that would mean that they've entered trader space which means that Ironclad would have to include them as a faction. The problem is that, as they've easily defeated an empire that could have wiped out the TEC and Advent several times, they would have to be super powerful which would destroy the balance, or they would have to be toned down which wouldn't fit to the background story.
I think that, if they are included, they will turn up in end game to forcefully end the match if it's taking too long. That would suit the story much better than having then being a normal faction.
