5. Avengers Vs Guardians Of The Galaxy
The Avengers and the Guardians of the Galaxy haven't really fought against each other properly in the comics, so this would be an original movie storyline if it happened (unless a comic was published with the two teams fighting between now and a potential movie release), but there's no denying it would be epic and, since both teams exist in the Marvel Cinematic Universe, there's no reason why it couldn't be possible in the movies. Thor, Hulk, Iron Man, Captain America, Black Widow, Hawkeye and whoever else joined the Avengers between now and then (Doctor Strange, Ant-Man, Black Panter etc) going up against the likes of Star-Lord, Drax the Destroyer, Gamora, Yondu, Groot and Rocket Raccoon in a live action epic would be astonishing and a sure-fire big draw for movie-goers. The Guardians of the Galaxy movie, which will be released in August of 2014, is said to be "very connected" to the Avengers sequel and, although this is most likely due to the two teams sharing a common foe in the Mad Titan Thanos, the likelihood of them clashing in a future certainly isn't out of the question.