Spoilers ahead. Avengers: Infinity War may be the high point the Marvel Cinematic Universe has built up to since Iron Man, but things definitely aren't headed downhill from here. In fact, Infinity War doesn't even mark the end of Marvel's Phase 3 run of films. Coming right up is Ant-Man and the Wasp, focusing on one of the main characters notably missing from the mega-crossover Infinity War. Given the discrepancy, fans are already wondering, does Ant-Man and the Wasp take place before or after Infinity War? Its positioning on the larger Marvel timeline has some very specific reasons for the timing, and some potential future consequences.
Focusing on the further adventures of Scott Lang (Paul Rudd), he and wife Hope van Dyne (Evangeline Lilly) try to balance family life and responsibilities with super heroics, but the consequences may be dire. According to Marvel's official press release, the film specifically takes place "in the aftermath of Captain America: Civil War." It's a very specific point and makes no mention of Infinity War, though we know Ant Man isn't present for the fight against Thanos.
Now that the official movie trailer for Ant-Man's, we have a better idea why. Lang asks van Dyne if she would've come to help with the events of Civil War if he asked; she doesn't answer directly, but sasses back "If you did, you wouldn't have been caught." That implies the giant ankle monitor slapped on Lang's leg is government-related, and likely the reason he couldn't join the battle against Thanos. The trailer has the heroes, and Professor Hank Pym, inventor of the shrinking technology they both use, on the run, another reason they weren't able to show up and assist against the Black Order's Earth invasion.
Directors of the upcoming fourth Avengers movie the Russo brothers won't confirm anything about the film, and are determined to leave the title a mystery for now, telling ScreenRant, "We are going to hang on to that title for awhile. We want people to just soak in the events of this movie, before thinking about what the next story is." Fan theories include events involving the Time or Reality stones, and with a good chunk of Ant-Man and the Wasp taking place in the Quantum Realm, there's some possibility that events from this film could set things up for the Avengers sequel.
It would help Ant-Man dovetail with the major storyline of the MCU; though the first Ant-Man was a semi-standalone film focusing on Lang and Professor Pym's shrinking technology, the sequel is more likely to weave in elements to tie it back into the Avengers. There's also the Marvel habit of releasing all films in the MCU in a fairly linear fashion, with even exceptions like Captain America: The First Avenger, acting more like long-form flashbacks for the ongoing events.
But with this movie definitely taking a step back in time, and the upcoming Captain Marvel film confirmed as a '90s flashback, it might be Marvel finally has the confidence fans will follow the films even through more convoluted timelines. Then again, Ant-Man and the Wasp opens July 6, and the next films slated for release are Captain Marvel, likely another flashback bookend, and then the next Avengers film. It's possible the fourth Avengers may tie all three films together, which would keep Marvel on track for linear continuity. Well, as linear as comic-book storylines get, anyway.
One thing is certain: Ant-Man and the Wasp won't show the effects of Thanos' devastating plan to destroy half the life in the universe. Whether or not any characters will ultimately perish into dust remains to be seen, but everyone on-screen in this brief pause from universal destruction is safe... for now.