12 Marvel Movies To Make Phase 4 "Distinctly Different"
2. Avengers Disassembled
There would be no braver event for the end of Phase 4 than killing off a massive swathe of the Avengers and leaving the team in ruins. Obviously focusing on internal frictions within the Avengers wouldn't exactly be a massive transition from what we're already seeing in Phase 3, but we haven't yet seen a hero break completely.
The idea of Scarlet Witch losing her mind and unwittingly turning her powers against her team-mates with fatal consequences would be a major departure from the model of introducing "villain of the week" candidates for each Phase. It would also completely change the dynamic of conquering evil and blur the lines of morality in a more substantial way than even Civil War.
Plus it would offer a perfect opportunity to retire some of the characters - like Ant-Man and Vision - introduced in Phase 2 as they age.
The Challenges
Kevin Feige has already confirmed that fans shouldn't expect to see a wild shift towards the dark side in the MCU, so a mass destruction event with very real fatalities might be a stretch too far. But then it is Feige who is promising a different approach, and a grim, melancholic Phase ender would undoubtedly fit that agenda.