The inevitable Justice League film will always be compared to The Avengers, because even now people are wondering how well it will stack up to Marvel's successful super-hero team up. If the Justice League movie is really aiming for a 2017 release, there are three major hurdles in the way of the JL movie, and there is no way on earth (or infinite earths!) that it will be able to clear all of them. Here's why.
1: Must include all the characters fans are expecting...
For two reasons, the DC film won't be able to do this. First is the number of heroes that established the team-- 8, including Batman and Superman. Some characters will need to be cut, perhaps Martian Manhunter, perhaps Aquaman (since their mainstream recognition and popularity are relatively low). Ditching them still leaves The Flash, Green Lantern, & Wonder Woman. But don't forget the current New 52 drops Martian Manhunter and includes Cyborg. So, no matter who else is in the film along with Bats and Supes, there will need to be, at minimum, 3 heroes that must be introduced, fleshed out, and given their spotlight moment. Clearing this hurdle would make the movie bloated, and would simultaneously make it impossible to leap over both of the remaining hurdles...
2: Must stay true to the tone of Man of Steel...
Does an Amazonian princess fit into the world of Man of Steel? Well, make her an alien, since we already have one of those... ditto Martian Manhunter. Okay... and Green Lantern got his ring (which functions in a very magical way, but whatever) from an alien. Wow, there sure are a lot of non-terrestrial beings on Earth all of a sudden. Give the writers, credit, maybe that's worked into the story line somehow. But it won't work to merely adjust the origins; these characters need to function in way that honors those origins within the emotional context and "real world feel" of Man of Steel. Additionally, the Justice League film needs to embrace these aliens but keep the potential vibrancy muted behind the dulled tones of the Man of Steel color pallet. None of this incorporates The Flash or Cyborg, who, again, need to come from somewhere (not space this time) and be integrated into the story without becoming the focus of the story. But let's say the film somehow managers to clear both the first and second hurdle, by some miracle. It cannot clear the third hurdle, which is...
3: Honor each character...
If there's one thing that has recently (oh that there were only one thing!) upset DC film fans, it has been when writers/directors dishonor their beloved characters. Superman doesn't kill. But he did. Batman is a detective, but rarely sleuths in three films. And he certainly doesn't quit being Batman for eight years. Now, I know this new universe will have an older, more world weary Batman. But what does that look like in the team-up film, and does it feel organic? DC's spotty track record not withstanding, bringing an Aquaman, for example, into this film universe, giving him powers that don't make him a joke, while still honoring his comic-book incarnation is a difficult task. Now do it for The Flash too... only wait, will it be the Wally West version, or the Barry Allen version? People love both incarnations.
Some fans believe the Arrow television show could provide a launch pad for characters like The Flash and circumvent one or more of these hurdles. However, it is possible that the TV show isn't even in the DC film continuity, and also conceivable that the show might "mess up" the origin stories or present versions of them that nobody wants to see on the big screen.
There's simply no way that the Justice League movie can clear all three of these hurdles. In 2017, the movie will come out, it will make a whole lot of money, but it will not rival The Avengers in any way, shape, or form. And if it fails to clear two or even all three hurdles, you can look forward to a Batman reboot in 2019.