To be honest I can see either or. On one hand, Shazam has the potential to be the most family friendly/kid appealing live action superhero movie even moreso than Spider-Man. It also wouldn't surprise me if they went the teamup route and put in Superman or Batman as Shazam's mentor (a la Iron Man in Homecoming). On the other hand, Captain Marvel has Nick Fury and potentially War Machine to help grosses, and the film before the storm (aka IW2 for the MCU), Disney also has Dumbo and Space (another Cars movie), they can double feature CM with throughout the Spring Break weeks. Also given the spot it's released on (International Women's Day) and the past success of Wonder Woman and Hunger Games, CM could go the distance but not $350M+ of course.