What I would have done in 2008
Back in 2008 the MCU had just stared. You could see they were going towards Avengers and WB had Nolan working out his Batman Trilogy that was committed to having no superheroes in the same universe. This was a tough spot.
I would have started developing a superhero universe right then, not waiting for Nolan to finish. That meant fast tracking Green Lantern and Superman. GL because he is an answer to Iron Man on the cultural and wish fulfillment levels. Will Smith coming off of Hancock I would have given him Green Lantern. Win over a great indie director, like Duncan Jones, fresh off of Moon with much better support and premise than he would have had for Source Code and put them on Green Lantern with some solid genre writers who can commit to a trilogy arc and hard sci fi. Superman would have gone to someone like Snyder with a different writing team, much more an alien disaster movie. Each of these franchises would be handled with the same level of depth that the Nolan franchise got. Let this be your only superhero for the universe. Run that.
2010 would hit, and we'd have Green Lantern
and Man of Steel
coming out from a Snyder who didn't have Sucker Punch on his record and a Duncan Jones Will Smith combo July 4th weekend. This is the year of Iron Man 2. All of a sudden, the balance between WB and DC shifts dramatically. But they're all in separate universes, what gives? But no Jonah Hex here, superheroes aplenty.
2011 brings Wonder Woman
as a mythic epic, get Brad Bird. Add a Flash as a television show, with the same team from Arrow using their same Flash movie script ideas. Nolan would finish the Batman trilogy with a push from the studio and no studio interference to try and make it fit with a Justice League, Dark Knight Rises
. Almost a direct response to Thor and and Captain America you have Wonder Woman and Batman.
2012 was the big deal, but instead of Batman going against the Avengers it'd be Man of Steel 2
against the Avengers. Put him out in April, the way TWS is this year. He's already repelled an alien invasion, now he's got to deal with the full wrath of his adopted planet, led by Lex Luthor. All the epicness you can muster. Let Green Lantern 2
hit July 4th again. Alas, no Men In Black 3. Too bad.
2013. Now the Avengers are out! How can WB "Catch up?" First, you drop Wonder Woman 2
early and Superman 3
late this year. Flash has been going strong for two years now. Do a Zatanna
show, or something like that as a spinoff of Flash. Charmed/Buffy-esque. It's a great time to be a superhero fan. IM3 still cleans up. Thor TDW still does okay.
2014. Now you spring the trap. This is when "Justice League: Secret Origins"
comes out. While Marvel is setting up GOTG, you drop Justice League July 4th weekend (with Will Smith in it
). The kicker: you film a whole Justice League trilogy back to back to back as a Crisis on Infinite Earths-like adaptation, where people from multiple universes (the League) has to come together and ends up merging all their worlds in the end!
2015. Finish it out, Wonder Woman 3 and Justice League: Crisis on Infinite Earths
here with Green Lantern 3 and Justice League: Final War
the following year. Avengers 2 and 3 still do well, but the sprawling Lord of the Rings-like epic of Justice League has already been told.
From there, WB has 4 epic trilogies in their stable, and can build from their extending any or all of their franchises. A new Batman franchise, since it's been laying resting for so long, the Justice League actor needs room to stretch his legs (assuming Bale didn't stay on). They can elevate Flash or Zatanna to a movie franchise, switch GL to a Hal-focused TV show. So many options.
What I'd do now.
After Batman vs Superman to introduce these characters, shoot Justice League as a trilogy all at once.