I was looking at the worldwide totals, and something kind of caught my eye. While I only went through the first 20 countries reporting for Endgame right now, nearly all of the countries are reporting that Endgame is ahead of where Avatar was at the same point in the cycle (of the 20 I looked at, only Greece and Spain did not have Endgame ahead of Avatar at the same point in the cycle, with many of the countries Endgame was already beating the total for Avatar...both Greece and Spain were only behind by a small bit). Now this will change quickly, as Avatar will certainly have better legs.
What caught my eye is that there is really only 5 countries that will see a huge deficit for Endgame compared to Avatar -- Japan, Russia, Spain, France and Germany. While Endgame was ahead in 4 out of the 5 (and approx. 35 million ahead at the same point in the cycle for all 5 countries), those 5 countries had huge runs for Avatar that led to an additional $568 million (an average of 113 million each). Endgame won't have the legs in those 5 countries to earn that (I don't think it will earn half of that). It still might make up for it from China, the US and how much more it is making in the other countries than Avatar did.