Re: Race changes that wouldn't bother you
Given that minorities were considered to be outside of the mainstream in US society when many of our most popular superheroes were created, some degree of colorblind casting has to take place. This is not only to be fair to actors and actresses of color, but also to better reflect the viewing audience, and also to attract foreign viewers in a market has become more and more dependent on international box office receipts. Personally, I have a sliding sale from least risky to most:
1) Villain (e.g. Kingpin, Electro, Mandarin, Bane), Supporting Character (e.g. Perry White, Alicia Masters, Harvey Dent, Heimdall), Underused Hero (e.g. Nick Fury, Wonderman) - Go ahead and make the change. No problems here.
2) Fully masked Iconic Hero (e.g. Spiderman, Deadpool) - Riskier than the first group, But given that the look of the character remains the same regardless of the person's race, it's ok so long as you have a damn good reason.
3) Cowled Iconic Hero (e.g. Batman, Captain America, Daredevil) - More difficult than the prior category, and easier for a character like Daredevil who is less well known and has yet to have a successful film.
4) Unmasked Iconic Hero (e.g. Superman, The Human Torch) Casting Michael B. Jordan as Johnny Storm would change the look of a character that has existed as both human and robot since 1939. You would have to have an extremely good reason to make a change under these circumstances
5) Race or Ethnic Specific Iconic Hero (e.g. Luke Cage, Black Panther, Tonto) Given the dearth of minority comic book heroes, under no circumstances should you change the race of these classic characters.