Square Enix revealed what the future holds in store for Marvel's Avengers and it appears there isn't much content to be had, probably due to an expansion launching just last month.
Marvel's Avengers had a troubled start and the next few months may or may not be all that different due to the lack of new content to play with. Technically, the devs have quite a few things to announce but they don't really sound like something that will keep players invested.
Anyway, August 2021 saw the release of War in Wakanda along with the arrival of the Black Panther but the next few months will not see any additions like that.
September will have the first-anniversary celebration that will offer an Iron Man outfit and anniversary bundle for free in the first week and a free Thor outfit along with an additional Hero's Catalyst in the second week. Priority Mission Rush, Cargo Synthoid and Flashback Rewards Cache will also pop up during the month.
Autumn and winter 2021 will have a bunch of returning things happening in the game with the only new hero event being exclusive to PlayStation systems.
Echoes will be a new enemy type that will arrive during this time but the announcement page didn't reveal too much about them, except that they are sound constructs created by Klaw.