Lmao dude it's gonna beat Avatar. The question is will it get to 3 billion. I don't think it will but it will be close. Passing Avatar is a foregone conclusion though so I don't know where you got your numbers.
3 billion definitely isn't happening anymore.
Movie is very front loaded.
In the US, it is down to doing IW numbers. Which means it can expect another $126m probably, so safe estimate is $854m total.
It has to make $159m elsewhere. It's also going to be a lot more frontloaded than IW was, especially because IW just launched in China during it's 3rd weekend.
Beating Avatar will probably happen, but it's not the guarantee that it was when the movie came out. It's going to be a bit of a crawl.