Is America racist because some people are upset that a black guy will be playing Johnny Storm?
First of all, who cares? Secondly, this is only an issue when we're dealing with a relatively known superhero. Nobody batted an eyelash when Samuel L. Jackson was cast as Nick Furry; a character who is white in the comics. Why? Because Nick Furry is not nearly as well known as the Fantastic Four. Maybe if they tried casting a black guy as Batman there would be some definite backlash.
A few notes about this movie and movies in particular:
For all of you claiming the Fantastic Four are "ruined" by casting Jordan as Johnny Storm, let me let you in on a little secret: nothing could ruin the Fantastic Four franchise any more than the last two movies. I feel embarrassed that I actually spent money to see the first one in the movie theater.
The only legitimate gripe I could see here is that Sue Storm and Johnny Storm are supposed to be siblings and if one of them is white and the other is black it doesn't really work as well as it could. You either have to pretend race doesn't exist or explain it by changing the story. Which brings me to my bigger point.
When you take a form of media (like a book or comic book) and adapt it to another form (like a movie or TV show), it's an interpretation. Always and every time. Stuff gets changed, some of it gets cut, or stuff gets added in. And to be honest, that's great. It's why I love both the Christopher Nolan Batman movies as well as the Tim Burton ones.
So I don't care if you want to change a character's back story. Or if you want to make him black instead of white. Or Asian, or Indian, or anything else. And I also don't care if you want to keep his racial background the same. It makes no difference to me.
Just make sure your movie is better than the Fantastic Four movies were.