Having writer's block at the moment so I'll just say this basic plotline for now:
Mazouz ain't recast. GCPD rooftop. Gordon, now with his signature glasses and stache, turns on the Bat signal and waits for you-know-who to arrive. Eventually, he does. He and Gordon talk for a bit about something, then he glides out.
Basically a giant homage to the ending of Batman Begins would be satisfying enough for me.