Batman has cleared his name or redeemed himself in the eyes of the GCPD. Gordon finally reignites the Batsignal. You hear yelling and car horns blowing in the street. Have a Bullock type officer smugly state they're rioting, but Gordon smiles as he looks down at the streets saying "No Detective, they're cheering." We get shots of civilians cheering and stuff, show the reactions of characters we've followed such as Alfred, Fox, and maybe a hint at the Joker ( laughter coming from inside an Arkham cell, and they're reactions. We see Batman at his parents grave, a robin lands on the tombstone. It looks at Bruce curiously before flying off. As Bruce watches the bird fly away, he looks up, notices the signal, fade to black.
Allow me to add a wrinkle, cut out the robin part, however do throw an Easter Egg in near the end or maybe the beginning of the film of the circus coming to town featuring a high-wire family act called "The flying Graysons".
Early in the film, maybe the opening scene, have Batman at his parent's grave in the rain, the toll of being Batman and taking the wrap for Two-face and Rachel's death all starting to emotionally take it's toll on him.
Now back to the final scene, after Gordon tells the detective that the crowd is cheering and we're seeing the reactions of Alfred & Fox, we see Batman, perched on the corner of a tall building and sees the Bat signal and then takes flight and glides over the crowd on his way to Police Headquarters...and the credits roll.