Will We Ever See a Marvel vs. DC Movie?

I and countless other fanboys-and-girls out there have long argued the epic question of our time: "Which is better, Marvel or DC?" (Read my blog post about it back in 2009). We all dreamed of the two universes colliding, and in comic book form at least, our wish was granted.  From the small but fun crossovers (Superman vs. Spider-man in 1976, Batman vs. The Incredible Hulk in 1981), to the more grand (DC vs. Marvel Comics mini-series in 1996 and JLA/Avengers in 2003/2004), we saw the two different superhero worlds collide.  A new fan trailer has sparked excitement by imagining what it would be like if the two distinct franchises were to unite for a mega-battle on the big screen.

Stitched together from various sources, it's a masterful editing job that makes me want to see the live-action battle royale to find out who would be left standing.  (It likely would end as a draw, with the good guys putting aside their differences to unite against a common foe.)

Would Disney and Warner Bros. ever join forces to make such a collaborative effort a reality?  Never say never.