DC has (4) shows coming on TV this season in addition to ARROW and, if you haven't noticed, DC is doing diversity right!
Jada Pinkett-Smith as Fish Mooney on GOTHAM is the casting coup on this show: she jumps off of the screen every time she's on! Along with being an excellent performer, her race and gender are less important than her ambition. She radiates ambition in a city that runs on criminality: she's the J.R. Ewing of GOTHAM!
Candice Patton as Iris West on THE FLASH is the right choice for a show that could easily play like a blizzard on rice. Everything about this concept screams HAPPY DAYS being visited by "MORK from Ork"; insulated and isolated from anything resembling an actual Central City; so putting Candice square in the middle of the romantic storyline gives just the right tilt to everything else that's racing around her!
With CAPTAIN AMERICA: THE WINTER SOLDIER (early 2014), Marvel has with Sam Wilson/The Falcon played by Anthony Mackie the first black character who isn't throwing race into everything because he's not trying to prove himself to anyone! Sam Wilson can't jog as fast as Steve Rogers (nobody can), so once that's established, Sam understands the bureaucracy better than Steve ever could, so Steve comes to Sam when everything hits the fan! As a fellow combat veteran, Steve is equally valuable in the field as he was on the streets: his partnering with Captain America is based on the content of his character, not the color of his skin! Sam Wilson is an excellent addition to the mighty Marvel movie universe!
Maybe Hollywood just can't settle what color they want her to be; black on STAR TREK, blue in AVATAR or green in GUARDIANS OF THE GALAXY; but GUARDIANS definitely benefited from having the graceful Zoe Saldana as Gamora! Gamora's decision to break from Ronan is the impetus for this non-team to join forces and she is nobody's damsel in distress when the heat is on!
Gamora in a co-ed prison? Feel sorry for the skels, not for her, baby!
Science fiction is the easiest place to diversify casting and it is wonderful to see both DC and Marvel taking advantage of that opportunity!