$2 billion is still very hard to reach. Apart from the two movies that got there in their original run only Titanic so far got close to that milestone (all the way back in 1997-1998, a reminder that Titanic remains the biggest box office phenomenon in modern times). Even reaching $1,5 billion isn't easy. No movie this year so far. As for something like Avengers 4 reaching $2 billion... forget it. Perhaps it's not strange on a site like this, but you see people overestimating the popularity of superhero-movies all the time. I remember comments that the first Spider-Man would beat Titanic. Some thought Batman v Superman would make $2 billion. And so on.