Okay here me out. Since the three factions left because of the coup FWC and the New Monarchy were involved and Dead Orbit taking them with them, this could be a chance to see the Concordat for the first time in ages again. I know this will be overlooked and probably not gonna be looked at but hear me out. Since there's now a power vacuum within the city, the Vanguard may now have another enemy on their hands to deal with and honestly this seems like a great opportunity for us to explore both the Concordat and the three factions that fled the city's lore. Lysander, given how important he was at the time might as well be the main focal point as he could be our potential enemy to try and overthrow the Vanguard. I really like this idea if guardians were sent to deal with this new threat only to find out that it'll take more than brute force to stop Concordat since they could sway the people of the city to their side, forcing the Vanguard to search for the three factions that fled and have them redeem themselves after trying to start a coup, banding them together to once again put an end to the Concordat and restore the city's order. But, that's probably just wishful thinking on my end. I know that this may not happened but it's something I would find interesting. If not then perhaps the Concordat will be dealt with the Vanguard way.