Here's my take on which characters "can" or "could" get such obvious changes as race - is the moviegoing public already familiar with them? This talk of "alternate universes" and such is complete bullcrap. How many of the millions of people who went to see
The Dark Knight ever actually read a Batman comic? Same for how many people saw
Spiderman, versus even the number of people who watched the old Spiderman cartoon? How many people who went to see
Iron Man 2, the most hyped movie in history, even knew Nick Fury was a comicbook character? I'd be astounded if it was even 5%.
Jude put it best, that making Spiderman black would be a stupidly obvious way of shoehorning tokenism into a very old liscence. But the real reason why you can make Nick Fury black but not Spiderman, is because only genuine nerds could or would complain about one, whereas the other, everyone who would go see a superhero movie already knows.
Apparently there's also a Batgirl. And a Nightwing and a Robin. And several other characters. Damn it, I'm not a Batman fan, this is just unfair! I can't keep track!
Nightwing was the original Robin, before he growed up, got tired of playing second banana, and set out to be a brooding antihero himself. The "current" Robin is actually the third one, not counting the girl Robin from "The Dark Knight Returns". Batgirl and Batwoman are two different characters - I don't really know who Batwoman is myself, except some kind of derange admirer or something. Batgirl was Commissioner Gordon's daughter who started out pretending to be Batman, but then "The Killing Joke" became cannon, and now "Batgirl" is "Oracle", Batman's resident Quest Compass and the comic world's hottest lesbian on wheels.
Black Spider-man wouldnt work.
But holy fuck why isnt Captain America Cherokee?
Because he didn't get his powers from being American. He was a soldier in WWII who got the Super Hero Serum. Not exactly a job the Army would have given to a non-white in the 1940s.