Next year two of the biggest comic book icons will meet on the screen for the first time. Batman Vs. Superman. This is the movie that will likely make or break DC's cinematic universe. It will be dark and gritty, like DC movies tend to be. It will also likely tackle some pretty heavy themes. Below are some of the topics I expect it might cover.
The most obvious theme will be religion. Besides the very well documented fact that Superman is a stand-in for Christ, the trailer made obvious that he is being worshiped as a god by some people. This of course is going to inspire a backlash by the faithful of the traditional religions. What will it mean for the Abrahamic religions to have a seemingly all powerful being show up? Not to mention the effect of confirming that we are not alone in the universe, and the religious implications of this. I expect this to be a big part of the movie.
Another one that seems inevitable is immigration. Let's face it, Superman is the ultimate undocumented alien. How does the government approach this? He has proved his value, does that give him a pass on the process? Since he was raised here, will they consider him to be naturalized? How can we be sure of his true sympathies and loyalties? I'm sure it will talk about the fear of people who are different from us, and the hostility that immigrants often face.
Liberty versus security is sure to be touched on. There seems to be two ways for them to portray this. The first is obviously Superman, and his ability to keep us all safe by bending us to his will. Some of the apparently dystopian imagery from the trailer may indicate they are taking this tack. The other is Batman, and the lengths he will go to punish those he considers a threat to society. There are rumors that he will employ a drone army of some sort. And he will take the decision of what should be done about Superman into his own hands. Whichever way they approach it, the question will be raised, "Is total security worth the loss of some or all liberty?"
The final theme is not as certain. Since Wonder Woman is in the film, there is a chance that feminism will be a strong theme. It all depends on how big a presence she has. If she has very much screen time, I think it is a given that woman's equality to man will at least be brushed up against. How can you have the strongest female character in pop culture and not touch on that? If she has a brief cameo though, we probably won't get anything that deep from her involvement.
Perhaps you think that this is a superhero movie is not going to deal with these controversial issues. Then you haven't been paying attention. Marvel tends to make lighter popcorn fare than DC (I say this as a self avowed Marvel fanatic, I happen to prefer the lighter touch usually), and even Captain America: The Winter Soldier dealt with questions of security, privacy, and pre-emptive action. Nolan's Batman Trilogy and Man of Steel both dealt with a myriad of weighty themes, and I fully expect this trend will continue.