It was fairly obvious that Avengers: Endgame was the closing of a major chapter of the MCU’s grand plan, signaling the departure of Tony Stark and Steve Rogers and effectively killing off Natasha Romanoff from the present timeline. However, with the defeat of Thanos, not only was the majority of Marvel’s heroes restored in the universe but the path was paved for a new generation of heroes to join the MCU, including Shang Chi, Monica Rambeau, and the Eternals, with many more to come. But as the universe expands, as do its threats, and if there’s going to be tangible stakes in future Marvel projects, that means not all of the Avengers are going to have their own happy endings.
Of course, the MCU could always kill off some beloved side characters, ala the death of Phil Coulson (depending on your version of MCU canon) and the Warriors Three, but with the contracts of their top stars coming to an end, don’t be too shocked if the likes of Hawkeye, Thor, Scarlet Witch, Peter Quill, or The Winter Soldier meet an untimely demise. In fact, the only character in the MCU who I could assume would be safe is T’Challa, as Feige has reiterated his intention to not kill off or recast T’Challa in the wake of the tragic 2020 passing of Chadwick Boseman, with the mantle likely being passed on to Letitia Wright’s Shuri, Danai Gurira’s Okoye, or Winston Duke’s M’Baku. As for T’Challa, one would assume the character would be retired, whether he’s riding into the sunset or serving a greater, cosmic purpose in parts unknown.