First off let's start with the timeline of the rumoured movie release dates that will be released in future years with solo movies before a Justice League team up movie.
Batman Begins - June 2005
The Dark Knight - July 2008
Green Lantern - June 2011
Batman 3 - July 2012
The Man of Steel - December 2012
The Flash - June 2013
Wonder Woman - August 2013
Aquaman - March 2014
Justice League - July 2014
(Where Green Lantern 2 fits into this remains to be seen. Sequels are 2-3 years away so that puts it in 2013/2014 more likely 2013 as they would want to focus on the JL movie. WB could push The Flash for May 2013 which would pit it against Iron Man 3 and fit Green Lantern into June/July with Wonder Woman August/September)
Now let's get down to business. "Batman Begins" is being referred to as "Action Comics #1" on the DC Entertainment thinking room table. "The Dark Knight" is "Action Comics #2" and "Green Lantern" will be "Action Comics #3".
Therefore there must be some sort of reference towards Batman or Gotham City within the Green Lantern movie just to let fans know that the movies are in safe hands. In the FIRST DRAFT of the Green Lantern script, Gotham City is mentioned as a place Green Lantern is seen saving people during a news montage. Will this still be in the movie? Time will tell.
"Batman 3" is "Action Comics 4#" and all fans know that Chris Nolan doesn't want to include himself into the DC Movie Universe club JUST yet. Therefore "Batman 3" will be a stand alone film linked exclusively to the first two. BUT, could some of WB's hierarchy persuade the Nolan brothers and Goyer to include a Superman reference? Especially since it will be released five month later? It would be every fan's dream.
"The Man of Steel" is the reboot produced by Christopher Nolan. He is going to be busy during the next two years and it will be "Action Comics 5#." To find out whether TMOS will include references to Green Lantern, Flash, Batman, or Bruce Wayne will probably depend on who the director will be and if he is willing to open his movie to include them. Nolan is pretty certain that TMOS will be separate in its "OWN" universe like the Batman films.
Here is my theory: Christopher Nolan is a massive Superman fan secretly and devotedly admires the "Superman: The Movie" and "Superman II" films. Could he be waiting to take the reigns of "The Man of Steel 2 and 3" to complete another DC trilogy? I believe so, which is why somebody like Jonathan Nolan or a pencil pusher could be in the director's chair for TMOS until Nolan has finished with Batman.
"The Flash" will be "Action Comics 6#" and is moving quickly, recently. This is the most likely to include references to other superheroes given that the Green Lantern writing team is penning the script. It is more likely to be in Green Lantern as the two are more closely linked in the comics.
"Wonder Woman" and "Aquaman" are "Action Comics 7#" and "8#" respectively and are still in early development. They are at least three years away which is plenty of time to get them ready. By the time they come out, there will already be cross overs in the DC universe, and will more than likely be heavily linked to other heroe--if not cameos in these movies.
What do you think of the DC Cross Over business? Have your say below! :D