Things are slightly different this year, in that Black Panther was released in February 2018 before the April debut of Infinity War, and Black Panther wasn’t expected to have a lot of spoilers that would influence Infinity War. This year, Captain Marvel arrives on March 8, 2019 and it is definitely expected to have a lot of spoilers that will influence Endgame the next month. Not only that, Endgame is being followed by Spider-Man: Far From Home, and the first Far From Home trailer has fans deeply confused about its timeline in relation to Avengers: Endgame.
Article source: https://www.cinemablend.com/news/2465410/when-is-the-next-avengers-endgame-trailer-coming-out