The question to me is would the world realistically treat Superman the same if he was black.
Yes, if it is written that way. As long as the writing is competent, it will all seem as "realistic" as comic movie premises ever do.
Granted maybe got a kind of good example in how to do it with the movie Hancock.
I'm glad you brought up Hancock. Now this was a movie that could have easily accommodated a racism storyline. I have no idea as to why they didn't but I can say that that not having that storyline didn't affect the quality of the moie. Most people's criticisms of that movie had nothing to do with missing a racism storyline.
One reason the Hancock writers probably didn't feel compelled to write a racism storyline was because Hancock wasn't black. The actor playing Hancock was black, but the character was not specifically any particular race.
The Hancock character was treated the same way all of the Superman characters have been treated, no particular race or religion. Likewise, Superman has never been "white". There is nothing about the character that demands he be "white", in-universe.
The only reason you and most others think the character is white is because Supes has always been played by a white actor. He was drawn as white in the comics solely because, how else would he have been drawn in the '30's?
In the end is I don't Superman to be edgy but I worry some fans will say they are avoiding race to make white people comfortable. Plus you will also have the usual racism but that like expecting water to be wet.
Fans (including you) need to become a bit more sophisticated in their thinking about race.
Demanding that race be an aspect of Superman's story solely because Superman is played by a black actor is "ghettoizing" black actors. It perpetrates the idea that "white" is the default setting and anything that is not part of that setting is "other" and requires an "explanation".
If presenting Jordan/Superman with no racial aspect is viewed by some as running away from dealing with racism, then so be it. That should be thought of as the viewers' problem.
There are intimate earth's, so doing like joker, doing an "Else world" where superman is black is quite acceptable.
Not really. Not to me. I want Jordan to play Kryptonian, Kal-El, son of Jor-El, raised in Smallville after coming to earth and being adopted by the Kents. There does not "need" to be even a hint of racism in Clark's childhood (or adulthood). I don't think there should be any alternate universe. Make it the real universe.
If the movie isn't as successful as they want it to be (just like most of it's predecessors), then re-cast the role with whomever (how about Idris Elba?), same as they have done with Routh and (perhaps) Cavil.