If only not so many good movies were not coming out one after another (Dead Pool, Incredibles 2, Jurassic Park and then Ant Man) it would have easily pass both Titanic and TFA. But now it might not even pass TFA.
Those didn't help. BP was definitely helped because it was really the only relevant release in its first 5-6 weeks. It even got a small boost thanks to IW, only dropping 4% the weekend IW released compared to its previous weekend. Passing TFA is still in the air. It all depends on how well IW does at the FBO in the coming weeks, as well as what kind of late push it gets from budget theaters/double features in the US. Personally, I think it has a pretty good chance at hitting #3 for WW.
For the past 3 weeks it has outpaced Jurassic World for the same point in time by 16.9% at the DBO. If that continued, and IW ends on Week 20, it will have made another $17.6M. Even if it remained flat, it would make another ~$15M. Of course, JW got a good push on Week 12, being put on an extra 665 screens. Considering both Avengers films have gotten similar pushes (Avengers got a massive 1,582 screen push, while AOU got a smaller 146 screen push, both on Week 18), I doubt IW will be any different. Worst case scenario, IW ends its DBO with ~$680M. Best case, it ends at ~$690M.
So, that leaves just $16.5-$26.5M for the FBO. If its the best case scenario, $16.5M is going to be easy to make up. However, $26.5M is definitely going to be tough. We won't get FBO til tomorrow, which is when I'll update the thread, so we can't really tell how well its done there this week.