If you haven't seen Avengers: Infinity War look away now, there are MAJOR spoilers ahead.
At the conclusion of Marvel's superhero team-up flick, Thanos gets his hands on all the Infinity Stones and snaps his fingers, erasing half of life in the galaxy. Viewers watched as Black Panther, Scarlet Witch, Spiderman, Falcon, Star-Lord, Drax, Groot, Dr. Strange, the Winter Soldier, and others turned to ash right in front of their eyes. Although the deaths were emotional for the on-screen characters (Tony Stark will never be the same), fans of the comic books knew that most of the heroes would find their way back to the world of the living, somehow.
Recently, Licensing Magazine revealed a synopsis for Avengers 4 (directors Joe and Anthony Russo refuse to reveal the actual title at the moment). LM also revealed the synopsis for Infinity War a year before it hit theaters, so it's safe to say they have a good record of presenting the facts. The synopsis reads: “A culmination of 22 interconnected films the fourth installment of the Avengers saga will draw audiences to witness the turning point of this epic journey. Our beloved heroes will truly understand how fragile this reality is and the sacrifices that must be made to uphold it."
The "fragile reality" part is causing fans to speculate that Marvel will employ some kind of an alternate reality, or time travel, to rework Thanos' evil deeds. Robert Downey Jr., Chris Evans, and Tom Hiddleston have all be seen on set wearing the same costumes they used in the first Avengers film, fueling the time travel theories even more. We'll see what rumors hold true when Avengers 4 hits theaters next May.