I don't at all agree that Hispanic people alone solely represent the immigrant experience.
There might a lot talk about it in the media but there a LOT of black and Asian immigrants to the U.S.
DC already have a black Superman that would have gained a lot of traction but for some reason they've neglected the character.
I'd absolutely love to see a black Superman. No other race or ethnicity in the United States has faced (or is currently facing) the explicit discrimination and hatred that black people get. I'm not saying that other races don't experience racism though but something about black people's position and struggles in the US just flat out sends some people crazy (just check the yahoo news comments section everyday to see what I'm talking about).
I'm not advocating changing Superman's race (like I said, DC already have a black Superman that could be explored) but a black Superman on this Earth (not the alternative Earths) would be very interesting because it would an extra wrinkle to the character. How would the average American (and the world as a whole) respond to a black Superman?