My assessment was right, this movie was very heavy front loaded as people wanted to avoid spoilers, especially after the way the first part ended.
Even with a re-release to try a cheap way to get the number 1 spot, it still struggled to spark a lot of interest. It is only a matter of how long are cinemas will continue to run it or fans for that matter willing to go again to try and beat Avatar
Actually, it's not that different from Avatar's initial run. Avatar was in theaters for 34 weekends, but earned only 9 million of its 749 million (domestic) in it's last 21 weekends. Avatar left theaters completely on August 8th 2010 and then returned with a legitimate re-release on August 27th 2010, called the Avatar: Special Edition. The "Special Edition" ran for 12 weekends and added 10.741 million domestic, and 22.469 million foreign to Avatar's Worldwide Total.
Endgame released on April 26th. Weekending June 23, it was still playing in 985 theaters. A week later, it expanded back into 2,025 theaters total. Labeling this expansion as a "re-release" is misleading, because it never actually left theaters completely.
Avatar (initial release 12/18/2009-8/8/2010) = $2,777,223,601 ($749,766,139 domestic + $2,027,457,462 foreign)
Avengers: Endgame (current release) = $2,772,469,552
So, without counting Avatar's actual 2010 Special Edition release that came out 37 weekends after Avatar's initial 2009 release, the 2 films are currently apart by only $4,754,049. Which is completely doable by the end of Endgame's current run. Then, maybe, Disney could do a legitimate re-release in 2020 that would be comparable to Avatar's Special Edition release of 2010.