>>130212963I feel like the best way to both wrap up the established themes and noir storyline AND hit the intended note that 'vengeance isn't enough' would be to have shit go sideways very publicly after Riddler gets caught and everything gets exposed. Riddler big explosive bomb isn't a terrorist attack, its him letting himself be caught so all of what he had documented hist the news and suddenly Gotham is tearing itself apart. Riots in the streets, officials fleeing in the dead of night, or getting assassinated left and right in a frantic attempt of those who didn't get exposed to silence any leads that would come back to them. Just total chaos as all of the corruption comes to a head at once and the people are mad as hell. You can even still have some variant of the shootout at the end, its just 'vigilantes' and rioters as opposed to a domestic terrorist group that work for Riddler. He might have planned for a response like theirs, but he didn't create them directly, etc.
That way you can still get rioters or vigilantes declaring that they are vengeance, giving Bruce pause as he sees what "justified anger" accomplishes and how this isn't want he wants, but its a more natural followup from the detective story and the ending still centers around the conspiracy and the corruption rather than the terrorism plotline wiping all of that out of the script and replacing it.