Through the official site of Disney for Australia, the first synopsis of Avengers: Endgame.
The first advance of the story does not reveal anything significant, but it does confirm that Thanos' actions will be confronted by the survivors, who will try to undo the “crack”.
“After the devastating events of Avengers: Infinity War, the universe is in ruins due to the effects of the crazy titan, Thanos. With the help of the remaining allies, the Avengers must meet once again to undo Thanos's actions and restore the order of the universe once and for all, no matter what the consequences may be. “
These last phrases, especially the fact that anticipated consequences to undo the actions of Thanos, arouse a single speculation: some kind of sacrifice will have to exist to restore “order”.