You know what idea I've had twirling around in my noggin for a while?
Is that after a lot of time has passed since GB (not too sure how much time has transpired since the events of GB2), but have the mayor… NOT the mayor. He is no longer the mayor, and the Ghostbusters have to get him back into power so he can abolish some laws against them being Ghostbusters again.
Could add a nice subplot. I dunno, guess it still needs some tweaking…