How about the acts of vengeance?
Unlike a Masters of Evil movie (which would require more of a team dynamic, and thus require 1 major villain and a bunch of henchmen) The Acts of Vengeance was a team of big hitters, who got together and switched enemies. An Acts of Vengeance style plotline would also keep the film from getting cluttered with 12 characters on the screen at once, since it would be more a one on one series of battles.
A link for those of you less familiar with the plot line.
MCU Rest of Decade prediction:
2015: Avengers: Age of Ultron, Ant-Man
2016: Captain America 3, Doctor Strange
2017: Thor 3, Guardians of the Galaxy 2, Inhumans
2018: Avengers 3, Black Panther, Incredible Hulk 2
2019: Iron Man 4, Doctor Strange 2, Ms. Marvel