This might happen if DC gets control over what movies they make. Seeing as how Marvel and DC agreed to do it in the books, it's plausible that they would do at big screens version. I mean somebody worked out Who Framed Roger Rabbit where Disney and WB toons appeared. I think DC won't let Superman lose a fight but Marvel is more than willing to let Thor lose for the sack of the project. So long as the number of characters and profit is split even, I think the would make it. Ultimately DC is in charge of their characters, not Snyder or Nolan. Marvel is more than willing to get different writers and directors if need be. A project like this should have Whedon writing and directing with Snyder contributing to fight scenes.
It might happen if people start petition now. Sure it won't come immediately but we'll put the word/idea out to the Studios and other fans. Even if it takes a decade for enough momentum to get the studios to make a movie, momentum has to start somewhere. Seriously, where is a good site to create a poll or petition the studios? I think we should just start now instead of saying it will never happening. This isn't impossible. We just have to be vocal enough for them to see the $$$$$$$. If JLA makes a billion, I think WB/DC would consider a crossover. This people put out some stupid sequels just because the franchise made so much money. They'll be willing to try if they think they can make $$$$$.
JLA/Avengers was a good crossover in the comics. I loved the way they incorporated the abstracts, artifacts, and various characters along with the amazing artwork.
I'll need to re-read it then as it's not the predominate Crossover that comes to mind. Sadly the superman/FF, the green lantern/silver surfer and some others are more clearer in my head.
Do you think the storyline of the comic would be a good foundation to build a 'when worlds collide' Movie?