The numbers aren't in Endgame's favor right now.
In the Domestic Box Office, Infinity War pulled in about 50 million from its 33rd to *140th day. Endgame is falling short on the day-by-day comparisons now, so it'll likely fall a fair bit short.
In the Foreign Box Office, Infinity War's 6th weekend made about 25 million. It managed to leg it another 47 million. Endgame only pulled in 17 million on its 5th weekend, so it's going to fade away a lot faster.
Even if Endgame performs exactly like Infinity War for the rest of its run, it still wouldn't be enough. But it's performing weaker in this stage and it's going to have to fend off Godzilla before Dark Phoenix even shows up.
Endgame will require a re-release to top Avatar, but Avatar could get a re-release of its own leading up to its sequels. Avatar has the edge here because it's still well-regarded in the Foreign Box Office and it would be more enticing given its ten year absence. Endgame, having just been released, isn't as likely have as broad an appeal. Home video and streaming services carves into that, but not nearly as many people have the means to enjoy Avatar in the full 3D that it's known for. I wouldn't bank on re-releases handing Endgame the coveted crown of the Worldwide Box Office, though Disney may certainly re-release both for a box office home run derby.
In either case, Zoe Saldana is in the two biggest movies of all time so she's probably feeling good no matter how it all plays out.
Edit: corrected 150th day to 140th day.
