It seems that this title is mostly possible as the source finds Trent Opaloch‘s website in which he listed credits which includes the name of Avengers 4’s title, End Game.
(Update: Trent Opaloch has removed the title of Avengers 4 from his website as Kevin Feige promise he would announce it later)
Check out the what source has said:
— GWW Presents: Omega Underground News (@OmegaUGround) June 30, 2018
If you don’t know about this guy, Trent Opaloch is the well-known cinematographer for the Marvel Studios’ MCU films likes of Captain America: The Winter Soldier, Captain America: Civil War, Avengers: Infinity War.
Its massive mistake by him making such great spoiler accidentally leak. According to Kevin Feige, it should be released after the release of the first teaser of Captain Marvel.
There would be a chance that Marvel is playing with us. This title could be a fake or working one that Trent has noted for a recording purpose.
But don’t know. Anything is possible in the universe of Marvel as no one expected Thanos’ snap effect.
Check out the official synopsis for Marvel’s Avengers: End Game
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
Joe and Anthony Russo direct Avengers 4. Starring Robert Downey Jr., Chris Hemsworth, Mark Ruffalo, Chris Evans, Scarlett Johansson, Benedict Cumberbatch, Don Cheadle, Tom Holland, Chadwick Boseman, Paul Bettany, Elizabeth Olsen, Anthony Mackie, Sebastian Stan, Tom Hiddleston, Idris Elba, Danai Gurira, Peter Dinklage, Benedict Wong, Pom Klementieff, Karen Gillan, Dave Bautista, Zoe Saldana, Vin Diesel, Bradley Cooper, Gwyneth Paltrow, Benicio del Toro, Josh Brolin, and Chris Pratt.
Avengers 4 is set to release on April 26, 2019.