When I made my formal prediction a month ago, I conservatively predicted a $160M opening weekend (and finals of $425M domestically and $1.1B worldwide). Im thrilled that the movie is crushing those numbers as I loved it. That CW cost as much as AoU is a little concerning, but in the end AoU was a few hundred million in the black, so Civil War should likewise make bank.
Immediately after watching CW, I thought the legs would be fantastic and in the ballpark of the 3.01 that Avengers earned. I now think that was a bit too optimistic as the general audience reaction, while very positive, isnt Avengers-like. MCU films have ranged from 2.35X opening weekend (IM3) to 3.53X (GoTG). I (optimistically) think the legs will be ~2.85X, an improvement over the last two Captain America movies (2.71 and 2.75 respectively). With a $179M OW, that would mean a finish around $510M. However, if it is slightly less leggy (which seems fairly likely) it will end up short of $500M (2.79).
Regardless of exactly where it finishes, CW is yet another big win for Disney. I think Deadline is being really conservative in predicting a 60% drop next weekend (and a $450M final). While I dont think a sub-50% drop is still in the cards, -55% seems more reasonable to me.