Avengers 4 Will Be The Final For Many Marvel Characters

Ever since Marvel Studios opted to shoot Avengers 3and 4 back-to-back, there’s been plenty of talk about these films as one giant conclusion to the MCU we know so far. For one, the decision to shoot both movies back-to-back ensures this may be the one and only time this giant cast of MCU regulars can be assembled—navigating the busy schedules of all these famous actors is something of a nightmare, but squeezing it into roughly a 12-month production period for two movies is much easier than asking them all to come back at an undetermined time down the road. Moreover, while Avengers 3 is called Avengers: Infinity War, the title of Avengers 4 is being held back because it’s “a spoiler.”
All of this has seemed to suggest that we’re going to see some character deaths and/or exits at the end of this whole thing, which really does mean the end of the MCU as we know it. And indeed that’s confirmed in a sprawling (and must-read) profile in Vanity Fairabout the 10-year anniversary of Marvel Studios:

"After Avengers 4, an ambitious multi-franchise crossover movie slated for release in 2019, at least some of the original characters who sit at the center of the billion-dollar Avengers team will be hanging up their capes and shields. Avengers 4 will “bring things you’ve never seen in superhero films: a finale. There will be two distinct periods. Everything before Avengers 4 and everything after. I know it will not be in ways people are expecting.”
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Credit Collider