Superman defeated an army of Kryptonians on his own and completely destroyed Metropolis/Manhattan in a fight that lasted 45 minutes. So to justify a Justice League film, you need a threat MORE DANGEROUS than an army of Kryptonians...
Even if Batman were like this
there is no way that a guy like Batman could survive in an apocalyptic situation if Kryptonian-level-or-stronger bad guys are gunning for him. And if the army can't really hurt people like this, then Batman can't either. The only way I can see Batman being on a team like this if if the Justice League does not trust the government for support and if the team needs a tech guy.
Now I believe that in the MoS universe, Cyborg would make a much better tech guy because he has alien tech that allows him to connect with any kind of computer. This means that if you put the team in an Independence Day situation in which they need to hack alien computers, it would make more sense for Cyborg to do this than Batman. In addition, Cyborg is more durable than Batman is. BUT I am not crazy. There is no way the studios would choose Cyborg over Batman. And I know that putting Cyborg on the team completely takes away the purpose of Batman in this universe as the tech guy.
Some people may believe that all you need to do is make Batman the leader, but he'd still be too flimsy to be one who lives very long. At least Captain America could take a full on hit from Thor. Batman cannot take a full on hit from Superman. And I don't think anyone else on the team would think that following the orders of a guy in a Bat costume with no powers is a good idea--no matter how bad*** he is. I mean, Superman took down an entire invasion on his own. Does he really need to be bossed around?
Then there's the Flash... Superman and Faora were so fast that sometimes you couldn't seem them until they made contact with an enemy. I don't know how they could make Flash any faster while remaining somewhat visible. If they can't do this though than Flash looks pointless. It doesn't help that Quicksilver will be showing up in two different Marvel projects soon. It may be very difficult to make the Flash look impressive enough to be justified without being so overpowered that he doesn't need a team himself... Still Flash is too popular to not be in the movie, right?
Moving on to Green Lantern... Marvel is making a Richard Rider movie apparently... Richard Rider is a brown-haired test pilot who is inducted into the Nova Corps, an intergalactic peace keeping organization. Who does this remind you of? That's right--Hal Jordan. This fact and the fact that the Hal Jordan Green Lantern film was such a bomb make me think that we won't see Hal Jordan in the Justice League movie. In addition, without having a role for Cyborg since his role was given to Batman, there is a need for racial diversity on the team. Every major summer block buster (Transformers, Avengers, Iron Man, Captain America, Thor, Star Trek, Pacific Rim, etc.) has a black character to help expand the movie's demographic, which brings in more money for the studio. Expect to see John Stewart as the Green Lantern in the Justice League for these reasons.
Obviously Wonder Woman will be in it. And it seems like the studio wants Aquaman in it. But I don't see the roster being more than 6 characters in the first movie. Avengers only had 6 heroes and one of them was hardly even used...
There are a lot more problems for the Justice League project then I realize. I mean after Avengers and Man of Steel, people must be getting sick of alien invasions in these films. And there are only so many alien invasions a world can take... But there needs to be multiple bad guys for multiple heroes.
I say the studios should just use Aquaman, Ocean Master, and the Atlantians as the villains in the Justice League movie. Then have Aquaman switch sides at the end.
In sum, Justice League is going to be a hard movie to pull off after Man of Steel glorified in so much violence for so long. And I think that the most likely roster for the team we will see is at this point is:
I like it.
I don't see Martian Manhunter happening after seeing so many alien invasions and seeing how he might diminish how special Superman seems. He'd also increase the cost of the film by a lot... Obviously no roster can please everyone. But this is how I see things shaking out at the moment...
Let me see your agreements and disagreements below, but please be rational rather than just being a rabid fanboy. People will take you more seriously.
P.S. Sorry for so much stream-of consciousness writing.