Back in May, while promoting Captain America: Civil War, directors Antony Russo and Joe Russo revealed that Avengers: Infinity War Part I and Avengers: Infinity War Part II will get new titles.
Avengers: Infinity War Part 1 has been changed to just Avengers: Infinity War and it will no longer be two movies.
Now that the Infinity War title is set, the guessing game shall begin as to what the fourth Avengers movie will be called.
Avengers 4 is currently going under the temporary title of Untitled Avengers, with the official title to be determined at a later date.