Green Arrow could be on par with the Batman films if done right only grittier and more fun considering Ollie's history.
DC has a ton of fantastic properties that they've been neglecting. For every Flash, Superman, Aquaman (yes he is rumored as well to be in preproduction) you'll see a scattering of Hawkman, Shazam!, The Atom....
Geoff Johns loves to take B list or C listers and make them A listers and he is a big part of DC Entertainment not to mention before the Iron Man film he was a B list characters people were completely unfamiliar with, I say B over C because he had cartoons but now he is literally one of the hottest designs out there. DC would love to fill the ranks so that the spotlight is lessened on Batman, Superman and Wonder Woman especially since they can't get Wondy off the ground.