Avengers: Infinity War is being framed as the culmination for the Marvel Cinematic Universe at-large, with major changes coming after the film - so much so that the title of the Avengers film that follows it is a spoiler. In an interview with Cinemablend, studio president Kevin Feige confirmed that the as-yet-untitled Avengers 4 has a title internally but that revealing it now would be a spoiler.
While Feige hasn't hinted that the title will resonate with comic book readers the same was he did before Captain America 3 was revealed as "Civil War," it's possible the film will borrow from another iconic Marvel comic book title ("Secret War(s)," anyone?)
Feige also revealed to Collider its former "Part 2" now separate productions and are no longer being filmed simultaneously as originally planned. Infinity War began shooting in January, and its follow-up is now scheduled to begin filming in August.
“We’re doing them one right after another... It became too complicated to cross-board them like that, and we found ourselves - again, something would always pay the price," said Feige. "We wanted to be able to focus and shoot one movie and then focus and shoot another movie.”
Warner Bros.'s Justice League progressed similiarly, with plans to film a sequel simultaneously were aborted during production.
Pulling back to a big picture, these next Avengers films are framed as so much of a game changer that Feige has now floated the idea of retiring the concept of "Phases" to denote eras in Marvel Studios' films.
“Certainly as we get to Infinity War there is a sense of a climax if not a conclusion to, by the time we’re at untitled Avengers 4, the 22 movies that will have encompassed the first three phases of the MCU. And what happens after that will be very different. I don’t know if it’s Phase 4, it might be a new thing.”
Avengers: Infinity War is scheduled for release May 4, 2018, with the fourth Avengers film following on May 3, 2019.