After reading Remedios Varo's post on Powder Room, the Forbes article linked in the post, I can't help but think that pointing to Guardians of the Galaxy as proof that they can make a successful movie with a minority lead is wishful thinking.
Some media folks have been trying to push Marvel to make a statement about their lack of non-white male leads by saying that Guardians of the Galaxy is weird, has characters no one has heard of and features a talking raccoon and a sentient tree.
Trouble is, Guardians of the Galaxy has a white male lead. It doesn't matter that the other parts of it are zany. It doesn't matter that Star Lord's compatriots are all aliens or genetically engineered critters. The guy at the helm of the ship is Chris Pratt who is very much whitey white white and presumably has a penis.
The Daily Beast seemed to be thinking along the same lines as I was after I read the post on Powder Room:
But Guardians isn't that diverse, really. Saldana and Bautista play space aliens who are colored different shades of green, while Del Toro and Hounsou serve very minor roles. The film's hero, Star-Lord, is played by Chris Pratt, a corn-fed blond, white guy from Minnesota—and the third major Marvel superhero played by a white guy named Chris, joining the broad-shouldered ranks of Chris Hemsworth (Thor) and Chris Evans (Captain America).
Basically, I feel like Guardians of the Galaxy is a great start in terms of moving toward having more diverse casts but it doesn't make me think Marvel will be pushed to take what they likely presume are "risks" with casting minority leads just because it did well.
It needs to happen but I think the focus needs to be on "These are the movies that people are interested in" and less on "Look at how well this kinda weird movie did so this means you can make movies with female/minority leads".